Benedicto Spinoza (1675)


Source: Ethics (1677). Everyman Classics, translation by G H R Parkinson, 1989; opening few pages from each of first four parts.

Concerning God


I. By CAUSE OF ITSELF (causa sui) I understand that whose essence involves existence; or, that whose nature cannot be conceived except as existing.

II. That thing is said to be FINITE IN ITS KIND (in suo genere finita) which can be limited by another thing of the same kind. E.g., a body is said to be finite because we can always conceive another larger than it. Thus a thought is limited by another thought. But a body cannot be limited by a thought, nor a thought by a body.

III. By SUBSTANCE (substantia) I understand that which is in itself and is conceived through itself: that is, that, the conception of which does not depend on the conception of another thing, from which conception it must be formed.

IV. By ATTRIBUTE (attributum) I understand that which the intellect perceives of substance as constituting its essence.

V. By MODES (modus) I understand the Modifications (affectiones) of a substance; or, that which is in something else through which it is also conceived.

VI. By God (Deus) I understand a being absolutely infinite, that is, a substance consisting of infinite attributes, each of which expresses eternal and infinite essence.

Explanation. - I say absolutely infinite, but not in its kind. For of whatever is infinite only in its kind, we can deny infinite attributes; but to the essence of what is absolutely infinite there appertains whatever expresses essence and involves no negation.

VII. That thing is said to be FREE (libera) which exists by the mere necessity of its own nature and is determined to act by itself alone. That thing is said to be NECESSARY (necessaria), or rather COMPELLED (coacta), which is determined by something else to exist and act in a certain fixed and determinate way.

VIII. I understand ETERNITY (aeternitas) to be existence itself, in so far as it is conceived to follow necessarily from the mere definition of an eternal thing.

Explanation.- For such existence is conceived as an eternal truth, just as is the essence of a thing, and therefore cannot be explained by duration or time, even though the duration is conceived as wanting beginning and end.


I. All things which exist, exist either in themselves or in something else.

II. That which cannot be conceived through another thing must be conceived through itself.

III. From a given determinate cause an effect follows of necessity, and on the other hand, if no determinate cause exists, it is impossible that an effect should follow.

IV. The knowledge of an effect depends on the knowledge of the cause, and involves it.

V. Things which have nothing in common reciprocally cannot be comprehended reciprocally through each other, or, the conception of the one does not involve the conception of the other.

VI. A true ideal must agree with that of which it is the idea (ideatum).

VII. The essence of that which can be conceived as not existing does not involve existence.


PROP. I. A substance is prior in nature to its modifications.

Proof.- This is obvious from Def. 3 and 5.

PROP. II. Two substances, having different attributes, have nothing in common between them.

Proof.- This also is obvious from Def. 3. For each of them must be in itself and be conceived through itself, or, the conception of one of them does not involve the conception of the other.

PROP. III. Of two things having nothing in common between them, one cannot be the cause of the other.

Proof.- If they have nothing in common reciprocally, it follows that (Ax. 5) they cannot be understood through each other, and therefore (Ax. 4) one cannot be the cause of the other. Q.e.d.

PROP. IV. Two or more distinct things are distinguished one from the other either by the difference of the attributes of substances or by the difference of their modifications.

Proof.- All things that exist, exist either in themselves or in something else (Ax. I), that is (Def. 3 and 5), outside the intellect nothing exists save substances and their modifications. Nothing therefore exists outside the intellect, through which several things may be distinguished one from the other except substances, or, what is the same thing (Def. 4), their attributes and modifications. Q.e.d.

PROP. V. There cannot exist in the universe two or more substances of the same nature or attribute.

Proof.- If several distinct substances exist, they must be distinguished one from the other either by the difference of their attributes or by the difference of their modifications (prev. Prop.). If, then, they are to be distinguished by the difference of their attributes alone, it is granted that there exists only one substance of the same attribute. But if they are to be distinguished by the difference of their modifications, then since a substance is prior in nature to its modifications (Prop. I), let the modifications be laid aside and let the substance be considered in itself, that is (Def. 3 and 6), truly considered; it could not then be conceived as distinguished from another, that is (prev. Prop.), two or more substances cannot have the same nature or attribute. Q.e.d.

PROP. VI. One substance cannot be produced by another.

Proof. - There cannot exist in the universe two substances of the same attribute (prev. Prop.), that is (Prop. 2), which have anything in common, and accordingly (Prop. 3) one of them cannot be the cause of the other or one cannot be produced by the other. Q.e.d.

Corollary. - Hence it follows that a substance cannot be produced from anything else. For there exists in the universe nothing save substances and their modifications, as is obvious from Ax. I and Def. 3 and 5: and it cannot be produced from another substance (prev. Prop.). Therefore a substance cannot be produced from anything else whatsoever. Q.e.d.

Another Proof. - This can be more easily shown by the method of proving the contrary to be absurd. For if a substance can be produced from anything else, the knowledge of it should depend on the knowledge of its cause (Ax. 4), and consequently (Def. 3 ) it would not be a substance.

PROP. VII. Existence appertains to the nature of substance.

Proof. - A substance cannot be produced from anything else (prev. Prop., Coroll.): it will therefore be its own cause, that is (Def. 1), its essence necessarily involves existence, or, existence appertains to its nature. Q.e.d.

PROP. VIII. Every substance is necessarily infinite.

Proof. - A substance of one attribute exists uniquely (Prop. 5), and it appertains to the nature of substance that it should exist (Prop. 7). It will therefore be of its nature to exist either finitely or infinitely. But not finitely. For (Def. 2) it would then be limited by some other substance of the same nature which also of necessity must exist (Prop. 7): and then two substances would exist having the same attribute, which is absurd (Prop. 5). It will exist, therefore, infinitely. Q.e.d.

Note I. - As to be finite is, in reality, a denial in part, and to be infinite is the absolute assertion of the existence of some nature, it follows, therefore (from Prop. 7 alone), that every substance must be infinite.

Note II. - I do not doubt that all those who judge about things in a confused way and are not wont to examine them through their first causes, may find it difficult to understand the proof of the seventh Proposition; doubtless because they do not distinguish between the modifications of substances and the substances themselves, and do not know in what manner things are produced. Hence it comes about that they apply the principle which they see in natural things to substances. For those who do not know the real causes of things confuse everything, and without the least mental repugnance they picture trees no less than men as speaking, and imagine men to be formed from stones no less than from seed, and any forms to be changed into any other forms whatsoever. So also those who confuse divine with human nature easily attribute human passions to God, more especially if they do not know how passions are produced in the mind. But if men would give heed to the nature of substance they would by no means doubt Prop. 7: rather it would be counted as an axiom by all, and included in the common notions. For then by substance they would understand that which is in itself, and through itself is conceived, that is, that the knowledge of which does not depend on the knowledge of any other thing; but by modification that which is in something else, and whose conception is formed from the conception of whatever it is in. Wherefore we may have true ideas of modifications which do not exist: since although they do not actually exist outside the mind, yet their essence is comprehended in something else, in such a way that it can be conceived through it. But the truth of substances does not exist outside the mind unless it exists in themselves, because through themselves they are conceived. If any one should say, then, that he has a clear and distinct, that is a true, idea of substance, and should nevertheless doubt whether such substance existed, he would indeed be like one who should say that he had a true idea and yet should wonder whether it were false (as will be manifest to any one who regards it carefully); or if any one should say that substance was created, he would state at the same time that a false idea had been made true, than which it is difficult to conceive anything more absurd. And therefore it must necessarily be acknowledged that the existence of substance, like its essence, is an eternal truth. And hence we may conclude in another manner that there cannot be two substances of the same nature: which it is now perhaps worth while to show. But let me arrange this in its proper order, therefore note: (1) the true definition of each thing involves nothing and expresses nothing but the nature of the thing defined. From which it follows (2) that clearly no definition involves any certain number of individuals nor expresses it, since the definition expresses nothing else than the nature of the thing defined. E.g., the definition of a triangle expresses nothing else than the simple nature of a triangle, but not a certain number of triangles. Let it be noted again (3) that for each existing thing there must be a cause by reason of which it exists. Note, moreover, that this cause, by reason of which something exists, must either be contained in the very nature and definition of an existing thing (clearly because it appertains to its nature to exist), or must exist outside itself. This granted, it follows that if a certain number of individuals exist in nature a cause must necessarily exist why those individuals, and not more or fewer, exist. E.g., if in the nature of things twenty men were to exist (whom for the sake of better explanation I will say to have existed at the same time, and that none existed before them), it would not be enough when giving a reason why twenty men existed, to show the cause of human nature in general, but it would be necessary also to show the cause why not more nor less than twenty existed: since (Note 3) a reason or cause should be given why each thing existed. But this cause cannot be contained in human nature itself (Notes 2 and 3), since the true definition of man does not involve the number twenty. Hence (Note 4) the reason why these twenty men exist, and consequently why each of them exists, must necessarily exist outside each one of them: and therefore it must be absolutely concluded that everything which is such that several individuals of that nature can exist must of necessity have an external cause if they are to exist. Now since, as has been shown already in this Note, existence appertains to the nature of substance, its definition must involve necessary existence, and therefore from its mere definition its existence can be concluded. But since, in Notes 2 and 3, we have shown that from its own definition the existence of several substances cannot follow, it follows necessarily therefore that only one substance of the same nature can exist, as we asserted.

PROP. IX. The more reality or being a thing has, the more attributes belong to it.

Proof. - This is obvious from Def. 4.

PROP. X. Each attribute of one substance must be conceived through itself.

Proof. - An attribute is that which the intellect perceives of a substance as constituting its essence (Def. 4), therefore (Def. 3) it must be conceived through itself. Q.e.d.

Note. - Hence it is manifest that, although two attributes are conceived as really distinct, that is, one is conceived without the aid of the other, we cannot thence conclude that they constitute two beings, or, two different substances. For it is of the nature of a substance that each of its attributes is conceived through itself: since all the attributes it has were always in it at the same time, nor could one of them be produced from another, but each of them expresses the reality or being of the substance. Therefore it is far from absurd to attribute several attributes to one substance; but on the contrary, nothing is more clear than that each entity must be conceived under some attribute, and the more reality or being it has, the more attributes it has which express both necessity or eternity and infinity; so that nothing can be clearer than that an absolutely infinite being must be defined (as we defined it in Def. 6), as a being which consists of infinite attributes, each of which expresses a certain eternal and infinite essence. But if any one still asks by what sign we shall be able to know the difference of substances, let him read the following Propositions, which will show that in the universe only one substance exists, and that is absolutely infinite, wherefore he will ask for that sign in vain.

PROP. XI. God or a substance consisting of infinite attributes, each of which expresses eternal and infinite essence, necessarily exists.

Proof. - If you deny it, conceive, if it be possible, that God does not exist. Then (Ax. 7) his essence does not involve existence. But this (Prop. 7) is absurd. Therefore God necessarily exists. Q.e.d.

Another Proof.- A cause or reason must be assigned for each thing, why it exists or why it does not. E.g., if a triangle exists, there must be a reason or cause why it exists; but if it does not exist, there must also be a reason or cause which prevents it from existing, or, which negates its existence. Now this reason or cause must be contained in the nature of the thing or outside of it. E.g., the reason why a square circle does not exist is shown by the very nature of the circle - namely, because it involves a contradiction. On the other hand, the existence of substance follows from its nature alone, for that involves existence (see Prop. 7). But the reason why a circle or triangle exists, or why it does not exist, does not follow from their nature, but from the order of universal corporeal nature. For from this it must follow either that a triangle necessarily exists or that it is impossible that it can now exist. But these matters are manifest of themselves. From which it follows that that must of necessity exist for which no reason or cause exists which could prevent its existence. If therefore no reason or cause can exist which prevents the existence of God or negates his existence, it must certainly be concluded that he does exist of necessity. But if such a reason or cause does exist, it must exist either in the nature of God itself or outside of it, that is, in another substance of another nature. For if it were of the same nature, thereby it would be admitted that God exists. But a substance of another nature has nothing in common with God (Prop. 2), and therefore can neither posit his existence nor negate it. And since the reason or cause which would negate God's existence cannot exist outside the divine nature it must of necessity then exist, if indeed God does not exist, in his own nature, which nature would therefore involve a contradiction. But to assert this of a being absolutely infinite and supremely perfect is absurd: therefore neither within God nor without him is there any cause or reason which could negate his existence, and consequently God must necessarily exist. Q.e.d.

Another Proof. - To be able not to exist is want of power, and on the other hand, to be able to exist is power (as is self-evident). If then that which now necessarily exists consists only of finite things, hence finite things are more powerful than a being absolutely infinite; and this, as is self-evident, is absurd. Therefore, either nothing exists, or a being absolutely infinite necessarily exists. But we ourselves exist, either in ourselves or in something else which exists of necessity, (see Ax. X and Prop. 7). Therefore a being absolutely infinite, that is (Def. 6) God, necessarily exists. Q.e.d.

Note. - In this last proof, I wished to show the existence of God a posteriori so that it might the more easily be perceived, and not because the existence of God does not follow a priori from the same basis of argument. For since ability to exist is power, it follows that the more reality belongs to the nature of some thing, the more power it will have to exist; and accordingly a being absolutely infinite, or God, has an absolutely infinite power of existence from itself, and on that account absolutely exists. Many, however, perhaps will not be able to see the truth of this proof easily, because they are accustomed to consider only those things which flow from external causes and of these, those which are quickly made, that is, which exist easily, they see perish easily; and on the other hand, they judge those things to be harder to make, i.e., not existing so easily, to which they think more features belong. But, to deliver them from these prejudices I need not show here in what respect this statement, 'that which is quickly made perishes speedily', is true, nor even whether, with respect to the whole of nature, all things are equally difficult or not; but it suffices to note that I do not speak here of things which are made from external causes, but of substances alone which (Prop. 6) cannot be produced from any external cause. For those things which are produced by external causes, whether they consist of many parts or few, whatever perfection or reality they have, it is all due to the power of their external cause, and therefore their existence arises merely from the perfection of some external cause and not their own. On the other hand, whatever perfection a substance may have is due to no external cause, wherefore its existence must follow from its nature alone, which is nothing else than its essence. Perfection, then, does not negate a thing's existence, but on the contrary, posits it; but imperfection, on the other hand, negates it, and so we cannot be more certain of the existence of anything than of the existence of a being absolutely infinite or perfect, that is, God. For since his essence excludes all imperfection and involves absolute perfection, by that very fact it removes all cause of doubt concerning his existence and makes it most certain: which will be manifest, I think, to such as pay it the least attention.

PROP. XII. NO attribute of a substance can be truly conceived, from which it would follow that substance can be divided.

25 pages omitted ...

Concerning the nature and origin of the mind


I NOW pass on to explain such things as must follow from the essence of God, or, of a being eternal and infinite: not all of them indeed (for infinite things in infinite ways must follow from that essence, as we have shown in Part I., Prop. 16), but only such as can lead us by the hand (so to speak) to the knowledge of the human mind and its consummate blessedness.


I. BY BODY (corpus) I understand a mode which expresses in a certain and determinate manner the essence of God in so far as he is considered as an extended thing (see Part I., Prop. 25)

II. I say that that appertains to the essence of a thing which, when granted, the thing itself is necessarily posited, and which, when negated, the thing is necessarily negated; or that without which the thing, or on the other hand, which without the thing can neither exist nor be conceived.

III. BY IDEA (idea) I understand a conception of the mind which the mind forms by reason of its being a thinking thing.

Explanation. - I say conception rather than perception, for the name perception seems to indicate that the mind is passive in relation to the object, while conception seems to express an action of the mind.

IV. BY ADEQUATE IDEA (idea adaequata) I understand an idea which, if it is considered in itself without relation to the object, has all the properties or intrinsic denominations of a true notion. - I say intrinsic in order that I may exclude what is extrinsic, i.e., the agreement between the idea and that of which it is the idea.

V. DURATION (duratio) is indefinite continuation of existing.

Explanation. - I say indefinite because it can in no wise be determined by means of the nature itself of an existing thing nor again by an efficient cause, which necessarily posits the existence of a thing but does not negate it.

VI. REALITY and PERFECTION (realitas et perfectio) I understand to be the same.

VII. BY PARTICULAR THINGS (res singulares) I understand things which are finite and have a determinate existence; but if several of them so concur in one action that they all are at the same time the cause of one effect, I consider them all thus far as one particular thing.


I. The essence of man does not involve necessary existence, that is, in the order of nature it can equally happen that this or that man exists as that he does not exist.

II. Man thinks.

III. The modes of thinking, such as love, desire, or whatever notions of the mind are distinguished by name, do not exist unless an idea in the same individual exists of the thing loved, Fired, etc. But an idea can exist although no other mode of thinking exists.

IV. We sense that a certain body is affected in many ways.

V. We neither sense nor perceive any particular things save bodies and modes of thinking. For Postulates, see after Prop. 13.


PROP. I. Thought (cogitatio) is an attribute of God, or, God is a thinking thing.

Proof. - Particular thoughts, or, this and that thought, are modes which express in a certain and determinate way the nature of God (Coroll., Prop. 25, Part I.). So the attribute whose conception all particular thoughts involve and through which they are conceived, belongs to God (Def. 5, Part I.). Thought, therefore, is one of the infinite attributes of God, which expresses the eternal and infinite essence of God (see Def. 6, Part I.), or God is a thinking thing. Q.e.d.

Note. - This proposition is also clear from the fact that we can conceive an infinite thinking being. For the more a thinking being can think, the more reality or perfection we conceive it to have. Therefore a being which can think infinite things in infinite ways is necessarily, by virtue of thinking, infinite. Since, therefore, from the mere consideration of thought we can conceive an infinite being, therefore necessarily (Defs. 4 and 6, Part I.) thought is one of the infinite attributes of God, as we wished to prove.

PROP. II. Extension (extensio) is an attribute of God, or God is an extended thing.

Proof. - This proof proceeds in the same manner as that of the previous proposition.

PROP. III. In God there necessarily exists not only the idea of his essence, but also the idea of all the things which follow necessarily from his essence.

Proof. - God can think infinite things in infinite ways (Prop. I, Part II.), or (what is the same thing, by Prop. 16, Part I.) he can form an idea of his essence and of all things which follow necessarily from it. Now all that is in the power of God necessarily exists (Prop. 35, Part I.). Therefore there exists such an idea, and that only in God (Prop. 15, Part I.). Q.e.d.

Note. - The generality of people understand by the power of God the free will of God and his right over all things that are, and so these are commonly considered contingent. For they say that God has the power of destroying everything and reducing it to nothing. Moreover, they very often compare the power of God to that of kings. But this in Coroll. 1 and 2, Prop. 32, Part I., we have refuted; and in Prop. 16, Part I., we showed that God acts by the same necessity by which he understands himself: that is, it follows from the necessity of the divine nature (as all grant unanimously) that God understands himself, and from the same necessity it follows that God performs infinite things in infinite ways. Again, in Prop. 34, Part I., we showed that the power of God is nothing else than the actual essence of God: and accordingly it is as impossible for us to conceive God inactive as to conceive him non-existent. And if I may pursue this subject further, I could furthermore point out that the power which the generality attribute to God is not only human power (showing that they conceive God to be a man or like to one), but also involves want of power. But I do not wish to return to this subject so many times. I only ask the reader again and again to turn over in his mind once and again what I have written on this subject in Part I., from Prop. 16 to the end. For no one can rightly perceive what I wish to point out unless he takes the greatest care not to confound the Power of God with the human power or right of kings.

PROP. IV. The idea of God from which infinite things in infinite ways follow can only be one.

Proof. - Infinite intellect comprehends nothing save the attributes and modifications of God (Prop. 30, Part I.). God is one (Coroll. I, Prop. 14, Part I.). Therefore the idea of God from which infinite things in infinite ways follow can only be one. Q.e.d.

PROP. V. The formal being of ideas acknowledges God as its cause only in so far as he is considered as a thinking thing, and not in so far as he is explained by some other attribute: that is, the ideas, not only of the attributes of God, but also of particular things, do not acknowledge those things of which they are the ideas, i.e., the objects perceived as their efficient cause, but God himself in so far as he is a thinking thing.

Proof.- This is obvious from Prop. 3 of this part. For there we concluded that God can form an idea of his essence and of all things which follow therefrom necessarily from the mere fact that he is a thinking thing, and not from the fact that he is the object of his idea. Wherefore the formal being of ideas acknowledges God for its cause in so far as he is a thinking thing. But this can be shown in another manner. The formal being of ideas is a mode of thinking (as is self-evident), that is (Coroll., Prop. 25, Part I.), a mode which expresses in a certain manner the nature of God in so far as he is a thinking thing, and therefore (Prop. 10, Part I.) involves the conception of no other attribute of God, and consequently (Ax. 4, Part I.) is the effect of no other attribute but thought. Therefore the formal being of ideas acknowledges God as its cause only in so far as he is a thinking thing, etc. Q.e.d.

PROP. VI. The modes of any attribute of God have God for their cause only in so far as he is considered through that attribute, and not in so far as he is considered through any other attribute.

Proof. - Each attribute is conceived through itself without the aid of another (Prop. 10, Part I.). Wherefore the modes of each attribute involve the conception of their attribute and not that of another; and so (Ax. 4, Part I.) the modes of any attribute of God have God for their cause only in so far as he is considered through that attribute, and not in so far as he is considered through any other attribute. Q.e.d.

Corollary. - Hence it follows that the formal being of things which are not modes of thinking does not follow from the divine nature because it has first known the things; but the things of which we have ideas follow and are concluded from their attributes in the same manner and by the same necessity as we have shown ideas to follow from their attribute of thought.

PROP. VII. The order and connection of ideas is the same as the order and connection of things.

Proof. - This is clear from Ax. 4, Part I. For the idea of everything that is caused depends on the knowledge of the cause of which it is an effect.

Corollary. - Hence it follows that God's power of thinking is equal to his actual power of acting: that is, whatever follows formally from the infinite nature of God, follows also invariably objectively from the idea of God in the same order and connection, in God.

Note. - Before we proceed further, let us call to mind what we have already shown above: that whatever can be perceived by infinite intellect as constituting the essence of substance, appertains to one substance alone; and consequently thinking substance and extended substance are one and the same substance, which is now comprehended through this and now through that attribute. Thus also a mode of extension and the idea of that mode are one and the same thing, but expressed in two ways, which certain of the Jews seem to have perceived indistinctly, for they said that God and his intellect and the things conceived by his intellect are one and the same thing. For example, a circle existing in nature and the idea of an existing circle which is also in God is one and the same thing, though explained through different attributes. And thus whether we consider nature under the attribute of extension or under the attribute of thought or under any other attribute, we shall find one and the same order and one and the same connection of causes: that is, the same things follow reciprocally. Nor did I say that God is the cause of (e.g.) an idea of a circle only in so far as he is a thinking thing, and of a circle only in so far as he is an extended thing, for any other reason than that the formal being of the idea of a circle can only be perceived through some other mode of thinking as its proximate cause, and that again through another, and so on to infinity: so that as long as things are considered as modes of thinking we must explain by the mere attribute of thought the order of the whole of nature or, the connection of causes; and in so far as things are considered as modes of extension, the order also of the whole of nature must be explained through the mere attribute of extension; and I understand the same of other attributes. Wherefore of things as they are in themselves, God is in truth the cause, forasmuch as he consists of infinite attributes; nor can I explain this more clearly at present.

PROP. VIII. The ideas of particular things (i.e. modes) which do not exist must be comprehended in the infinite idea of God in the same way as the formal essences of particular things (modes) are contained in the attributes of God.

... 40 pages omitted...

Concerning the origin and nature of the emotions

MOST who have written on the emotions and on the manner of human life, seem to have dealt not with natural things which follow the universal laws of nature, but with things which are outside the sphere of nature: they seem to have conceived man in nature as a kingdom within a kingdom. For they believe that man disturbs rather than follows the order of nature, and that he has absolute power over his actions, and is not determined by anything else than himself. They then attribute the cause of human weakness and inconstancy not to the universal power of nature, but to some defect or other in human nature, wherefore they deplore, ridicule, despise, or, what is most common of all, abuse it: and he that can carp in the most eloquent or acute manner at the weakness of the human mind is held by his fellows as almost divine. Yet excellent men have not been wanting (to whose labour and industry I feel myself much indebted) who have written excellently in great quantity on the right manner of life, and left to men counsels full of wisdom: yet no one has yet determined, as far as I know, the nature and force of the emotions and what the mind can do in opposition to them for their constraint. I know that the most illustrious Descartes, although he also believed that the human mind had absolute power over its actions, endeavoured to explain the human emotions through their first causes, and to show at the same time the way in which the mind could have complete control over the emotions: but, in my opinion, he showed nothing but the greatness and ingenuity of his intellect, as I shall show in its proper place. For I wish to revert to those who prefer rather to abuse and ridicule the emotions and actions of men than to understand them. It will doubtless seem most strange to these that I should attempt to treat on the vices and failings of men in a geometrical manner, and should wish to demonstrate with sure reasoning those things which they cry out against as opposed to reason, as vain, absurd, and disgusting. My argument, however, is this. Nothing happens in nature which can be attributed to a defect of it: for nature is always the same, and its virtue and power of acting is everywhere one and the same, that is, the laws and rules of nature according to which all things are made and changed from one form into another, are everywhere and always the same, and therefore there must be one and the same way of understanding the nature of all things, that is, by means of the universal laws and rules of nature. Therefore such emotions as hate, anger, envy, etc., considered in themselves, follow from the same necessity and virtue of nature as other particular things: and therefore they acknowledge certain causes through which they are understood, and have certain properties equally worthy of our knowledge as the properties of any other thing, the contemplation alone of which delights us. And so I shall treat of the nature and force of the emotions, and the power of the mind over them, in the same manner as I treated of God and the mind in the previous parts, and I shall regard human actions and appetites exactly as if I were dealing with lines, planes, and bodies.


I. I call that an ADEQUATE CAUSE (adaequata causa) whose effect can clearly and distinctly be perceived through it. I call that one INADEQUATE or PARTIAL (inadaequata seu partialis) whose effect cannot be perceived through itself alone.

II. I say that we ACT when something takes place within us or outside of us whose adequate cause we are, that is (prev. Def.), when from our nature anything follows in us or outside us which can be clearly and distinctly understood through that nature alone. On the other hand, I say we are PASSIVE (pati) when something takes place in us or follows from our nature of which we are only the partial cause.

III. By EMOTION (affectus) I understand the modifications of the body by which the power of action of the body is increased or diminished, aided or restrained, and at the same time the ideas of these modifications.

Explanation. - Thus if we can be the adequate cause of these modifications, then by the emotion I understand an ACTION (actio), if otherwise a PASSION (passio).


I. The human body can be affected in many ways whereby its power of acting is increased or diminished, and again in others which neither increase nor diminish its power of action.

This postulate or axiom is dependent on Post. I and Lemmas 5 and 7, which see, post Prop. 13, Part II.

II. The human body can suffer many changes and yet retain the impressions or traces of objects (Post. 5, Part II.), and consequently the same images of things (Note, Prop. I7, Part II.).


PROP. I. Our mind acts and also is passive: namely, in so far as it has adequate ideas, thus far it necessarily acts, and in so far as it has inadequate ideas, thus far it necessarily is passive.

Proof. - The ideas of every human mind are some adequate and some mutilated and confused (Note, Prop. 40, Part II.). But the ideas which are adequate in the mind of any one are adequate in God in so far as he constitutes the essence of that mind (Coroll., Prop. 11, Part II.), and those again which are inadequate in the mind of any one are also adequate in God, (same Coroll.), not in so far as he contains in himself solely the essence of the given mind, but in so far as he contains the minds of other things at the same time. Again, from any given idea some effect must necessarily follow (Prop. 36, Part I.), and of this effect God is the adequate cause (Def. I, Part III.), not in so far as he is infinite, but in so far as he is considered as affected by that given idea (Prop. 9, Part II.). But of that effect of which God is the cause, in so far as he 15 affected by an idea which is adequate in the mind of some one, that same mind is the adequate cause (Coroll., Prop. 11, Part II.). Therefore our mind (Def. 2, Part III.), in so far as it has adequate ideas, necessarily acts: which was the first point. Then whatever follows from an idea which is adequate in God, not in so far as he has in himself the mind of one man only, but in so far as he has in himself the minds of other things at the same time with the mind of this man, of that effect (Coroll., Prop. 11, Part II.) the mind of that man is not the adequate but merely the partial cause. And so (Def. 2, Part III.) the mind, in so far as it has inadequate ideas, necessarily is passive: which was the second point. Therefore our mind, etc. Q.e.d.

Corollary.- Hence it follows that the mind is more subject to passions according as it has more inadequate ideas, and, on the other hand, it acts more the more adequate ideas it has.

PROP. II. The body cannot determine the mind to think, nor the mind the body to motion, nor to rest, nor to any other state (if there be any other).

Proof.- All modes of thinking have God for their cause, in so far as he is a thinking thing and not in so far as he is explained by another attribute (Prop. 6, Part II.). Therefore that which determines the mind to think is a mode of thinking and not of extension, that is (Def. I, Part II.), it is not a body: which was the first point. Again, the motion and rest of a body must arise from another body, which also was determined to motion or rest by another body, and absolutely everything which arises in a body must have arisen from God in so far as he is considered as affected by some mode of extension and not some mode of thinking (Prop. 6, Part II.), that is, it cannot arise from a mind, which (Prop. 11, Part II.) is a mode of thinking: which is the second point. Therefore the body cannot, etc. Q.e.d.

Note. These points are more clearly understood from what was said in the Note on Prop. 7, Part II., namely, that the mind and body are one and the same thing, which is now conceived under the attribute of thought, now under the attribute of extension. Whence it comes about that the order or concatenation of things is one, or, nature is conceived now under this, now under that attribute, and consequently that the order of the actions and passions of our body is simultaneous in nature with the order of actions and passions of our mind. This also is clear from the manner in which we proved Prop. I2, Part II. But although the situation is such that no reason for doubt can remain, yet I scarcely believe, unless I confirm the matter by experience that men can be induced to consider this calmly: so firmly are they persuaded that the body is moved by the mere command of the mind, or is kept at rest, and that it performs many things which merely depend on the will or ingenuity of the mind. For no one has thus far determined the power of the body, that is, no one has yet been taught by experience what the body can do merely by the laws of nature, in so far as nature is considered merely as corporeal and what it cannot do, save when determined by the mind. For no one has yet had a sufficiently accurate knowledge of the construction of the human body as to be able to explain all its functions: in addition to which there are many things which are observed in brutes which far surpass human sagacity, and many things which sleep-walkers do which they would not dare, were they awake: all of which sufficiently shows that the body can do many things by the laws of its nature alone at which the mind is amazed. Again, no one knows in what manner, or by what means, the mind moves the body, nor how many degrees of motion it can give to the body, nor with what speed it can move it. Whence it follows when men say that this or that action arises from the mind which has power over the body, they know not what they say, or confess with specious words that they are ignorant of the cause of the said action, and have no wonderment at it. But they will say that whether they know or not how the mind moves the body, they have found by experience that unless the mind is apt for thinking the body remains inert: again, that they have learnt from experience that it is in the power of the mind alone to speak or be silent, and many other things which they therefore believe to depend on the decision of the mind. But as for the first point, I ask them whether experience has not also taught them that when the body is inert the mind likewise is inept for thinking? For when the body is asleep and at rest the mind, at the same time, remains asleep, and has not the power of thinking that it has when awake. Again, I think all have discovered by experience that the mind is not at all times equally apt for thinking about one and the same object: but according as the body is more apt, so that the image of this or that object may be excited in it, so the mind is more apt for regarding this or that object. But they will say that it cannot come about from the laws of nature alone, in so far as nature is regarded only as corporeal, that the causes of buildings, pictures, and things of this kind, which are made by human skill alone, can be deduced, nor can the human body, save if it be determined and led thereto by the mind, build a temple, for example. But I have already shown that they know not what a body can do, or what can be deduced from mere contemplation of its nature, and that they have experience of many things which happen merely by reason of the laws of nature, which they would never have believed could happen save by the direction of the mind, as those things which sleepwalkers do at which they are surprised when they are awake; and I may here draw attention to the construction of the human body, which far surpasses any piece of work made by human art, to say nothing of what I have already shown, namely, that from nature, considered under whatsoever attribute, infinite things follow. As for their second point, surely human affairs would be far happier if the power in men to be silent were the same as that to speak. But experience more than sufficiently teaches that there is nothing less under men's control than their tongues, or less in their power than the control of their appetites. Whence it comes about that many believe that we are free in respect only of those things which we desire only moderately, for then we can restrain our desire for those things by the recollection of something else which we frequently recollect: but with respect to those things which we seek with great emotion, and that nothing can obliterate from the mind, we are by no means free. But in truth, if they did not experience that we do many things for which we are sorry afterwards, and that very often when we are harassed by contrary emotions we 'see the better, yet follow the worse', there would be nothing to prevent them from believing that we do all things freely. Thus an infant thinks that it freely seeks milk, an angry child thinks that it freely desires vengeance, or a timid child thinks it freely chooses flight. Again, a drunken man thinks that he speaks by the free decision of the mind those things which, were he sober, he would keep to himself. Thus a madman, a talkative woman, a child, and people of such kind, think they speak by the free decision of the mind, when, in truth, they cannot put a stop to the impulse to talk. So experience teaches as clearly as reason that men think themselves free on account of this alone, that they are conscious of their actions and ignorant of the causes of them; and moreover that the decisions of the mind are nothing save their appetites, which are various according to various dispositions of the body. For each one manages everything according to his emotion, and thus those who are assailed by conflicting emotions know not what they want: those who are assailed by none are easily driven to one or the other. Now all these things clearly show that the decision of the mind, and the appetite and the determination of the body, are simultaneous in nature, or rather one and the same thing, which when considered under the attribute of thought and explained through the same we call a decision (decretum), and when considered under the attribute of extension and deduced from the laws of motion and rest we call a determination (determinatio), which will appear more clearly from what will be said on the subject. For there is another point which I wish to be noted specially here, namely, that we can do nothing by a decision of the mind unless we recollect having done so before, e.g., we cannot speak a word unless we recollect having done so. Again, it is not within the free power of the mind to remember or forget anything. Wherefore it is believed that all that is within the power of the mind is the ability to keep to ourselves or speak, according to the decision of the mind alone, the thing we recollect. But when we dream that we speak, we think that we speak from the free decision of the mind, yet we do not speak, or if we do, it is due to a spontaneous motion of the body. We dream again that we conceal something from men, and think that we do so by the same decision of the mind as that by which, when we are awake, we are silent concerning what we know. Finally, we dream that we do certain things by a decision of the mind which were we awake we would dare not: and therefore I should like to know whether there are in the mind two sorts of decisions, fanciful and free? But if our folly is not so great as that, we must necessarily admit that this decision of the mind, which is thought to be free, cannot be distinguished from imagination or memory, nor is it anything else than the affirmation which an idea, in so far as it is an idea, necessarily involves (Prop. 49, Part II.).

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On human servitude, or the strength of the emotions


HUMAN lack of power in moderating and checking the emotions I call servitude. For a man who is submissive to his emotions does not have power over himself, but is in the hands of fortune to such an extent that he is often constrained, although he may see what is better for him, to follow what is worse. I purpose accordingly in this part to show the cause of this, and what there is good and bad in the emotions. But before I begin I will preface something concerning perfection and imperfection, and then good and bad.

He that determines to do anything, and finishes it, calls it perfect, and not only does he say this, but so does any one else who rightly knows, or thinks he knows, the mind of the author of that work and his design. For example, if any one sees some work (which I suppose not yet finished), and knows that the design of the author of that work is to build a house, he will call that house imperfect, and on the contrary, he will call it perfect as soon as he sees it brought to the end which its author determined to give to it. But if any one sees some piece of work the like of which he had never seen, and does not know the mind of the artificer, he clearly will not know whether the work be perfect or not. This seems to have been the first meaning of these words. But afterwards, when men began to form universal ideas and to think out exemplars of houses, buildings, towers, etc., and to prefer certain exemplars to others, it came about that every one called that perfect which he saw to agree with the universal idea which he had formed of that sort of thing, and on the contrary, imperfect what he saw less agree with the exemplar that he had conceived, although in the opinion of the artificer it might be perfect. There seems to be no other reason that men should call natural things which are not made with human hands perfect or imperfect: for men are wont to form universal ideas of natural as well as artificial things, which they regard as exemplars to which nature looks for guidance (for they think that nature does nothing without some end in view). When, therefore, they see something to take place in nature which less agrees with the exemplar that they have conceived of that kind of thing, they think that nature has been guilty of error or has gone astray and has left that thing imperfect. We see thus that men have been wont to call things of nature perfect or imperfect from prejudice rather than from a true knowledge, for we showed in the appendix of the first part that nature does not act with an end in view: for that eternal and infinite being we call God or nature acts by the same necessity as that by which it exists, for we showed that it acts from the same necessity of its nature as that by which it exists (see Prop. 16, Part I.).

Therefore the reason or cause why God or nature acts and why it exists is one and the same; therefore, as God exists with no end in view, he does not act with any end in view, but has no principle or purpose either in existing or acting. A cause, then, that is called 'final' is nothing save human appetite itself in so far as it is considered as the principle or primary cause of something. E.g., when we say that habitation is the final cause of this or that house, we understand nothing else than this, that man had an appetite for building a house from his imagining the conveniences of domestic life. Wherefore habitation, in so far as it is considered as a final cause, is nothing save this particular appetite, which in truth is the efficient cause which is considered as primary because men are commonly ignorant of the causes of their appetites. For they are, as I have already said, conscious of their actions and appetites, but ignorant of the causes by which they are determined to seek something. The common saying of the vulgar, that nature sometimes is guilty of error and goes astray and produces imperfect things, I count among the fabrications which I dealt with in the appendix of Part I. Therefore perfection and imperfection are in truth only modes of thinking, namely notions, which we are wont to invent owing to the fact that we compare with each other individuals of the same species or genus. And on that account (see above, Def. 6, Part II.) I said that by reality and perfection I understood the same thing. For we are wont to refer all individuals of nature to one class which we call most general, namely, to the notion of being which appertains absolutely to all individuals of nature. In so far as we refer the individuals of nature to this one class, and compare them with each other, and find that some have more reality or being than others, thus far we call some more perfect than others; and in so far as we attribute to them something which involves negation, as limit, end, weakness, etc., thus far we call them imperfect, inasmuch as they do not affect our mind as much as those which we call perfect, and not because there is something wanting in them which is theirs, or that nature has gone astray. For nothing belongs to the nature of anything except that which follows from the necessity of the nature of the efficient cause, and whatever follows from the necessity of the nature of the efficient cause, necessarily happens.