Proposition 39: He who hates anyone will endeavour to do him an injury, unless he fears that a greater injury will come to himself; He who loves anyone will seek to benefit him.
Proof: To hate a man is (3.13 note) to conceive him as a cause of pain
Therefore he who hates a man will try to remove or destroy him.
But if anything more painful, or, in other words, a greater evil, should accrue to the hater thereby—and if the hater thinks he can avoid such evil by not carrying out the injury, which he planned against the object of his hate—he will desire to abstain from inflicting that injury (3.28)
the strength of his endeavour (3.37) will be greater than his former endeavour to do injury, and will therefore prevail over it. Q.E.D.
Note: By good I here mean every kind of pleasure, and all that conduces thereto, especially that which satisfies our longings, whatsoever they may be.
By evil, I mean every kind of pain, especially that which frustrates our longings.
For I have shown (3.9 note) that we in no case desire a thing because we deem it good, but, contrariwise, we deem a thing good because we desire it: consequently we deem evil that which we shrink from; everyone, therefore, according to his particular emotions, judges or estimates what is good, what is bad, what is better, what is worse, lastly, what is best, and what is worst.
Thus a miser thinks that abundance of money is the best, and want of money the worst.
An ambitious man desires nothing so much as glory, and fears nothing so much as shame.
To an envious man nothing is more delightful than another's misfortune, and nothing more painful than another's success.
So every man, according to his emotions, judges a thing to be good or bad, useful or useless.
The emotion, which induces a man to turn from that which he wishes, or to wish for that which he turns from, is called timidity, which may accordingly be defined as the fear whereby a man is induced to avoid an evil which he regards as future by encountering a lesser evil (3.28).
But if the evil which he fears be shame, timidity becomes bashfulness.
Lastly, if the desire to avoid a future evil be checked by the fear of another evil, so that the man knows not which to choose, fear becomes consternation, especially if both the evils feared be very great.
Proposition 40: He, who sees himself as hated by another, and believes that there is no cause for hatred, will hate that other in return.
Proof: He who conceives another as affected with hatred, will thereupon be affected himself with hatred (3.27), that is, with pain, accompanied by the idea of an external cause.
But, by the hypothesis, he conceives no cause for this pain except him who is his enemy.
Therefore, from conceiving that he is hated by some one, he will be affected with pain, accompanied by the idea of his enemy.
In other words, he will hate his enemy in return. Q.E.D.
Note: He who thinks that he has given just cause for hatred will (3.30 and note) be affected with shame.
But this case (3.25) rarely happens.
This reciprocation of hatred may also arise from the hatred, which follows an endeavour to injure the object of our hate (3.39).
He therefore who conceives that he is hated by another will conceive his enemy as the cause of some evil or pain.
Thus he will be affected with pain or fear, accompanied by the idea of his enemy as cause.
In other words, he will be affected with hatred towards his enemy, as I said above.
Corollary 1: He who conceives, that one whom he loves hates him, will be a prey to conflicting hatred and love.
For, in so far as he conceives that he is an object of hatred, he is determined to hate his enemy in return.
But, by the hypothesis, he nevertheless loves him: wherefore he will be a prey to conflicting hatred and love.
Corollary 2: If a man conceives that one, whom he has hitherto regarded without emotion, has done him any injury from motives of hatred, he will forthwith seek to repay the injury in kind.
Proof: He who conceives, that another hates him, will (by the last proposition) hate his enemy in return, and (3.26) will endeavour to recall everything which can affect him painfully;
He will moreover endeavour to do him an injury (3.39).
Now the first thing of this sort which he conceives is the injury done to himself; he will, therefore, forthwith endeavour to repay it in kind. Q.E.D.
Note: The endeavour to injure one whom we hate is called Anger.
The endeavour to repay in kind injury done to ourselves is called Revenge.
Proposition 41: If anyone conceives that he is loved by another, and believes that he has given no cause for such love, he will love that other in return. (Cf. 3.15 Coroll., and 3.16)
Proof: This proposition is proved in the same way as the preceding one. See also the note appended thereto.
Note: If he believes that he has given just cause for the love, he will take pride therein (3.30 and note).
This is what most often happens (3.25), and we said that its contrary took place whenever a man conceives himself to be hated by another (see note to preceding proposition.)
This reciprocal love, and consequently the desire of benefiting him who loves us (3.39), and who endeavours to benefit us, is called gratitude or thankfulness.
It thus appears that men are much more prone to take vengeance than to return benefits.
Corollary: He who imagines that he is loved by one whom he hates, will be a prey to conflicting hatred and love.
This is proved in the same way as the first corollary of the preceding proposition.
Note: If hatred be the prevailing emotion, he will endeavour to injure him who loves him.
This emotion is called cruelty, especially if the victim be believed to have given no ordinary cause for hatred.
Proposition 42: He who has conferred a benefit on anyone from motives of love or honour will feel pain, if he sees that the benefit is received without gratitude.
Proof: When a man loves something similar to himself, he endeavours, as far as he can, to bring it about that he should be loved thereby in return (3.33).
Therefore he who has conferred a benefit confers it in obedience to the desire, which he feels of being loved in return; that is (3.34) from the hope of honour or (3.30 note) pleasure.
Hence he will endeavour, as far as he can, to conceive this cause of honour, or to regard it as actually existing.
But, by the hypothesis, he conceives something else, which excludes the existence of the said cause of honour:
Wherefore he will thereat feel pain (3.19). Q.E.D.
Proposition 43: Hatred is increased by being reciprocated, and can on the other hand be destroyed by love.
Proof: He who conceives, that an object of his hatred hates him in return, will thereupon feel a new hatred, while the former hatred (by hypothesis) still remains (3.40).
But if, on the other hand, he conceives that the object of hate loves him, he will to this extent (3.38) regard himself with pleasure, and (3.29) will endeavour to please the cause of his emotion.
In other words, he will endeavour not to hate him (3.41), and not to affect him painfully; this endeavour (3.37) will be greater or less in proportion to the emotion from which it arises.
Therefore, if it be greater than that which arises from hatred, and through which the man endeavours to affect painfully the thing which he hates, it will get the better of it and banish the hatred from his mind. Q.E.D.
Proposition 44: Hatred which is completely vanquished by love passes into love: and love is thereupon greater than if hatred had not preceded it.
Proof: The proof proceeds in the same way as Prop. 38 of this Part.
For he who begins to love a thing, which he was wont to hate or regard with pain, from the very fact of loving feels pleasure.
To this pleasure involved in love is added the pleasure arising from aid given to the endeavour to remove the pain involved in hatred (3.37), accompanied by the idea of the former object of hatred as cause.
Note: Though this be so, no one will endeavour to hate anything, or to be affected with pain, for the sake of enjoying this greater pleasure.
That is, no one will desire that he should be injured, in the hope of recovering from the injury, nor long to be ill for the sake of getting well.
For everyone will always endeavour to persist in his being, and to ward off pain as far as he can.
If the contrary is conceivable, namely, that a man should desire to hate someone, in order that he might love him the more thereafter, he will always desire to hate him.
For the strength of love is in proportion to the strength of the hatred, wherefore the man would desire, that the hatred be continually increased more and more, and, for a similar reason, he would desire to become more and more ill, in order that he might take a greater pleasure in being restored to health: in such a case he would always endeavour to be ill, which (3.6) is absurd.
Proposition 45: If one thinks that anyone similar to himself hates anything also similar to himself, which he loves, he will hate that person.
Proof: The beloved object feels reciprocal hatred towards him who hates it (3.40).
Therefore the lover, in conceiving that anyone hates the beloved object, conceives the beloved thing as affected by hatred, in other words (3.13), by pain.
Consequently he is himself affected by pain accompanied by the idea of the hater of the beloved thing as cause.
That is, he will hate him who hates anything which he himself loves (III. xiii. note). Q.E.D.
Proposition 46: If a man has been affected pleasurably or painfully by another person representing a different class or nation, the man will love or hate that person and the whole class or nation for that person.
Proof: This is evident from 3.16.
Proposition 47. Joy arising from the fact, that anything we hate is destroyed, or suffers other injury, is never unaccompanied by a certain pain in us.
Proof: This is evident from 3.27 For in so far as we conceive a thing similar to ourselves to be affected with pain, we ourselves feel pain. Note: This proposition can also be proved from the Corollary to 2.17.
Whenever we remember anything, even if it does not actually exist, we regard it only as present, and the body is affected in the same manner;
wherefore, in so far as the remembrance of the thing is strong, a man is determined to regard it with pain; this determination, while the image of the thing in question lasts, is checked by the remembrance of other things excluding the existence of the aforesaid thing, but is not destroyed.
Hence, a man only feels pleasure in so far as the said determination is checked:
for this reason the joy arising from the injury done to what we hate is repeated, every time we remember that object of hatred.
For, as we have said, when the image of the thing in question, is aroused, inasmuch as it involves the thing's existence, it determines the man to regard the thing with the same pain as he was wont to do, when it actually did exist.
However, since he has joined to the image of the thing other images, which exclude its existence, this determination to pain is forthwith checked, and the man rejoices afresh as often as the repetition takes place.
This is the cause of men's pleasure in recalling past evils, and delight in narrating dangers from which they have escaped.
For when men conceive a danger, they conceive it as still future, and are determined to fear it.
This determination is checked afresh by the idea of freedom, which became associated with the idea of the danger when they escaped therefrom: this renders them secure afresh: therefore they rejoice afresh.
Proposition 48: Love or hatred towards, for instance, Peter is destroyed, if the pleasure involved in the former, or the pain involved in the latter emotion, be associated with the idea of another cause: and will be diminished in proportion as we conceive Peter not to have been the sole cause of either emotion. Proof: This Proposition is evident from the mere definition of love and hatred (3.13 note).
For pleasure is called love towards Peter, and pain is called hatred towards Peter, simply in so far as Peter is regarded as the cause of one emotion or the other. When this condition of causality is either wholly or partly removed, the emotion towards Peter also wholly or in part vanishes. Q.E.D.
Proposition 49: Love or hatred towards a thing, which we conceive to be free, must, other conditions being similar, be greater than if it were felt towards a thing acting by necessity. Proof: A thing which we conceive as free must (1. Def. 7) be perceived through itself without anything else.
If, therefore, we conceive it as the cause of pleasure or pain, we shall therefore (3.13 note) love it or hate it, and shall do so with the utmost love or hatred that can arise from the given emotion.
But if the thing which causes the emotion be conceived as acting by necessity, we shall then (by the same Def. 7, Part 1) conceive it not as the sole cause, but as one of the causes of the emotion, and therefore our love or hatred towards it will be less. Q.E.D.
Note: It follows that men, thinking themselves to be free, feel more love or hatred towards one another than towards anything else: to this consideration we must add the imitation of emotions treated of in 3.27, 3.34, 3.40 and 3.43. Proposition 50: Anything whatever can be, accidentally, a cause of hope or fear. Proof: This proposition is proved in the same way as 3.15, which see, together with the note to 3.18. Note: Things which are accidentally the causes of hope or fear are called good or evil omens.
Now, in so far as such omens are the cause of hope or fear, they are (by the definitions of hope and fear given in 3.18 note) the causes also of pleasure and pain;
Consequently we, to this extent, regard them with love or hatred, and endeavour either to invoke them as means towards that which we hope for, or to remove them as obstacles, or causes of that which we fear.
It follows, further, from 3.25, that we are naturally so constituted as to believe readily in that which we hope for, and with difficulty in that which we fear; moreover, we are apt to estimate such objects above or below their true value.
Hence there have arisen superstitions, whereby men are everywhere assailed.
However, I do not think it worth while to point out here the vacillations springing from hope and fear.
It follows from the definition of these emotions, that there can be no hope without fear, and no fear without hope, as I will duly explain in the proper place.
Further, in so far as we hope for or fear anything, we regard it with love or hatred; thus everyone can apply by himself to hope and fear what we have said concerning love and hatred.
Proposition 51: Different men may be differently affected by the same object, and the same man may be differently affected at different times by the same object. Proof: The human body is affected by external bodies in a variety of ways (2. Post. 3).
Two men may therefore be differently affected at the same time, and therefore (by Ax. 1 after Lemma 3 after 2.13) may be differently affected by one and the same object.
Further (by the same Post.) the human body can be affected sometimes in one way, sometimes in another.
Consequently (by the same Axiom) it may be differently affected at different times by one and the same object. Q.E.D.
Note: We thus see that it is possible, that what one man loves another may hate, and that what one man fears another may not fear; or, again, that one and the same man may love what he once hated, or may be bold where he once was timid, and so on.
Again, as everyone judges according to his emotions what is good, what bad, what better, and what worse (3.39. note), it follows that men's judgments may vary no less than their emotions,
hence when we compare some with others, we distinguish them solely by the diversity of their emotions, and style some intrepid, others timid, others by some other epithet.
For instance, I shall call a man intrepid, if he despises an evil which I am accustomed to fear;
if I further take into consideration, that, in his desire to injure his enemies and to benefit those whom he loves, he is not restrained by the fear of an evil which is sufficient to restrain me, I shall call him daring.
Again, a man will appear timid to me, if he fears an evil which I am accustomed to despise; and if I further take into consideration that his desire is restrained by the fear of an evil, which is not sufficient to restrain me, I shall say that he is cowardly; and in like manner will everyone pass judgment.
 This is possible, though the human mind is part of the divine intellect, as I have shown in 2.13 note.
Lastly, a man may be affected with pleasure at one time and with pain at another time, accompanied by the idea of himself as cause.
This arises from:
the inconstancy of human judgment and,
Man often judges things solely by his emotions.
the fact that things that cause of pleasure or pain are often purely imaginary.
This does not include the uncertainty of things alluded to in 3.28
Thus, we can easily understand what are Repentance and Self-complacency.
Repentance is pain, while self-complacency is pleasure, accompanied by the idea of one's self as cause.
These emotions are most intense because men believe themselves to be free (3.49).
Proposition 52: An object which we have formerly seen in conjunction with others, and which we do not conceive to have any property that is not common to many, will not be regarded by us for so long, as an object which we conceive to have some property peculiar to itself. Proof: As soon as we conceive an object which we have seen in conjunction with others, we at once remember those others (2.28 and note).
Thus we pass forthwith from the contemplation of one object to the contemplation of another object.
And this is the case with the object, which we conceive to have no property that is not common to many.
For we thereupon assume that we are regarding therein nothing, which we have not before seen in conjunction with other objects.
But when we suppose that we conceive an object something special, which we have never seen before, we must needs say that the mind, while regarding that object, has in itself nothing which it can fall to regarding instead thereof;
Therefore it is determined to the contemplation of that object only. Therefore an object, etc. Q.E.D.
Note: Wonder is the mental modification, or imagination of a particular thing.
Consternation is this imagination excited by fear.
Wonder at an evil keeps a man so engrossed in its simple contemplation, that he cannot think of anything else to avoid the evil.
Veneration is wonder towards a person's prudence, industry, or anything of that sort, as that person is thereby regarded as far surpassing ourselves.
Otherwise, wonder at a man's anger, envy, etc., is called Horror.
Our love will be greater if we have wonder for the prudence, industry, etc of a man we love (3.12).
If we add veneration to this wonder, then it is called Devotion.
We may in like manner conceive hatred, hope, confidence, and the other emotions, as associated with wonder; and
we should thus be able to deduce more emotions than those which have obtained names in ordinary speech.
Whence it is evident, that the names of the emotions have been applied in accordance rather with their ordinary manifestations than with an accurate knowledge of their nature.
Wonder is the opposite of Contempt.
It generally arises:
when we see someone wondering at, loving, or fearing something, or
when something intially appears to be like things, which we wonder at, love, fear, etc.
In consequence (3.15 Coroll. and 3.27) we are determined to wonder at, love, or fear that thing.
But if from the presence, or more accurate contemplation of the said thing, we are compelled to deny concerning it all that can be the cause of wonder, love, fear, etc., the mind then, by the presence of the thing, remains determined to think rather of those qualities which are not in it, than of those which are in it; whereas, on the other hand, the presence of the object would cause it more particularly to regard that which is therein.
As devotion springs from wonder at a thing which we love, so does Derision spring from contempt of a thing which we hate or fear, and Scorn from contempt of folly, as veneration from wonder at prudence.
Lastly, we can conceive the emotions of love, hope, honour, etc., in association with contempt, and can thence deduce other emotions, which are not distinguished one from another by any recognized name.
Proposition 53: When the mind regards itself and its own power of activity, it feels pleasure which is proportional to the distinctness wherewith it conceives itself and its own power of activity.
Proof: A man does not know himself except through the modifications of his body, and the ideas thereof (2.19 and 2.23).
When, therefore, the mind is able to contemplate itself, it is thereby assumed to pass to a greater perfection, or (3.11 note) to feel pleasure; and the pleasure will be greater in proportion to the distinctness, wherewith it is able to conceive itself and its own power of activity. Q.E.D.
Corollary: This pleasure is fostered more and more, in proportion as a man conceives himself to be praised by others.
For the more he conceives himself as praised by others, the more he will imagine them to be affected with pleasure, accompanied by the idea of himself (3.29 note);
Thus he is (3.27) himself affected with greater pleasure, accompanied by the idea of himself. Q.E.D.
Proposition 54: The mind endeavours to conceive only such things as assert its power of activity.
Proof: The endeavour or power of the mind is the actual essence thereof (III. vii.).
But the essence of the mind obviously only affirms that which the mind is and can do; not that which it neither is nor can do.
Therefore the mind endeavours to conceive only such things as assert or affirm its power of activity. Q.E.D.
Proposition 55: When the mind contemplates its own weakness, it feels pain thereat.
Proof: The essence of the mind only affirms that which the mind is, or can do;
In other words, it is the mind's nature to conceive only such things as assert its power of activity (last Prop.).
Thus, when we say that the mind contemplates its own weakness, we are merely saying that while the mind is attempting to conceive something which asserts its power of activity, it is checked in its endeavour——in other words (3.11. note), it feels pain. Q.E.D.
Corollary: This pain is more and more fostered, if a man conceives that he is blamed by others;
This may be proved in the same way as the corollary to 3.53.
Note: This pain, accompanied by the idea of our own weakness, is called humility;
The pleasure, which springs from the contemplation of ourselves, is called self—love or self—complacency.
And inasmuch as this feeling is renewed as often as a man contemplates his own virtues, or his own power of activity, it follows that everyone is fond of narrating his own exploits, and displaying the force both of his body and mind, and also that, for this reason, men are troublesome to one another.
Again, it follows that men are naturally envious (3.24. note, and 3.32. note), rejoicing in the shortcomings of their equals, and feeling pain at their virtues.
For whenever a man conceives his own actions, he is affected with pleasure (3.53.), in proportion as his actions display more perfection, and he conceives them more distinctly—that is (2.40. note), in proportion as he can distinguish them from others, and regard them as something special.
Therefore, a man will take most pleasure in contemplating himself, when he contemplates some quality which he denies to others.
But, if that which he affirms of himself be attributable to the idea of man or animals in general, he will not be so greatly pleased.
He will, on the contrary, feel pain, if he conceives that his own actions fall short when compared with those of others.
This pain (3.28.) he will endeavour to remove, by putting a wrong construction on the actions of his equals, or by, as far as he can, embellishing his own.
It is thus apparent that men are naturally prone to hatred and envy, which latter is fostered by their education.
For parents are accustomed to incite their children to virtue solely by the spur of honour and envy.
But, perhaps, some will scruple to assent to what I have said, because we not seldom admire men's virtues, and venerate their possessors.
In order to remove such doubts, I append the following corollary.
Corollary: No one envies the virtue of anyone who is not his equal. Proof: Envy is a species of hatred (3.24. note) or (3.13. note) pain, that is (3.11. note), a modification whereby a man's power of activity, or endeavour towards activity, is checked.
But a man does not endeavour or desire to do anything, which cannot follow from his nature as it is given.
Therefore a man will not desire any power of activity or virtue (which is the same thing) to be attributed to him, that is appropriate to another's nature and foreign to his own.
Hence his desire cannot be checked, nor he himself pained by the contemplation of virtue in some one unlike himself, consequently he cannot envy such an one.
But he can envy his equal, who is assumed to have the same nature as himself. Q.E.D.
Note: When, therefore, as we said in the note to 3.52., we venerate a man, through wonder at his prudence, fortitude, etc., we do so, because we conceive those qualities to be peculiar to him, and not as common to our nature.
We, therefore, no more envy their possessor, than we envy trees for being tall, or lions for being courageous.
Proposition 56: There are as many kinds of pleasure, of pain, of desire, and of every emotion compounded of these, such as vacillations of spirit, or derived from these, such as love, hatred, hope, fear, etc., as there are kinds of objects whereby we are affected. Proof: Pleasure and pain, and consequently the emotions compounded thereof, or derived therefrom, are passions, or passive states (3.11. note).
Now we are necessarily passive (3.1.), in so far as we have inadequate ideas; and only in so far as we have such ideas are we passive (3.3i.).
That is, we are only necessarily passive (2.40. note), in so far as we conceive, or (2.17. and note) in so far as we are affected by an emotion, which involves the nature of our own body, and the nature of an external body.
Wherefore the nature of every passive state must necessarily be so explained, that the nature of the object whereby we are affected be expressed.
Namely, the pleasure, which arises from, say, the object A, involves the nature of that object A, and the pleasure, which arises from the object B, involves the nature of the object B;
Wherefore these two pleasurable emotions are by nature different, inasmuch as the causes whence they arise are by nature different.
So again the emotion of pain, which arises from one object, is by nature different from the pain arising from another object, and, similarly, in the case of love, hatred, hope, fear, vacillation, etc.
Thus, there are necessarily as many kinds of pleasure, pain, love, hatred, etc., as there are kinds of objects whereby we are affected.
Now desire is each man's essence or nature, in so far as it is conceived as determined to a particular action by any given modification of itself (3.9. note).
Therefore, according as a man is affected through external causes by this or that kind of pleasure, pain, love, hatred, etc.
In other words, according as his nature is disposed in this or that manner, so will his desire be of one kind or another, and the nature of one desire must necessarily differ from the nature of another desire, as widely as the emotions differ, wherefrom each desire arose.
Thus there are as many kinds of desire, as there are kinds of pleasure, pain, love, etc., consequently (by what has been shown) there are as many kinds of desire, as there are kinds of objects whereby we are affected. Q.E.D.
Note: Among the kinds of emotions, which, by the last proposition, must be very numerous, the chief are luxury, drunkenness, lust, avarice, and ambition, being merely species of love or desire, displaying the nature of those emotions in a manner varying according to the object, with which they are concerned.
For by luxury, drunkenness, lust, avarice, ambition, etc., we simply mean the immoderate love of feasting, drinking, venery, riches, and fame.
Furthermore, these emotions, in so far as we distinguish them from others merely by the objects wherewith they are concerned, have no contraries.
For temperance, sobriety, and chastity, which we are wont to oppose to luxury, drunkenness, and lust, are not emotions or passive states, but indicate a power of the mind which moderates the last—named emotions.
However, I cannot here explain the remaining kinds of emotions (seeing that they are as numerous as the kinds of objects), nor, if I could, would it be necessary.
It is sufficient for our purpose, namely, to determine the strength of the emotions, and the mind's power over them, to have a general definition of each emotion.
It is enough to understand the general properties of the emotions and the mind, to enable us to determine the quality and extent of the mind's power in moderating and checking the emotions.
Thus, though there is a great difference between various emotions of love, hatred, or desire, for instance between love felt towards children, and love felt towards a wife.
There is no need for us to take cognizance of such differences, or to track out further the nature and origin of the emotions.
Proposition 57. Any emotion of a given individual differs from the emotion of another individual, only in so far as the essence of the one individual differs from the essence of the other. Proof: This proposition is evident from Ax. i. (which see after Lemma 3. Prop. 13, Part 2).
Nevertheless, we will prove it from the nature of the three primary emotions.
All emotions are attributable to desire, pleasure, or pain, as their definitions above given show.
But desire is each man's nature or essence (3.9. note).
Therefore desire in one individual differs from desire in another individual, only in so far as the nature or essence of the one differs from the nature or essence of the other.
Again, pleasure and pain are passive states or passions, whereby every man's power or endeavour to persist in his being is increased or diminished, helped or hindered (3.11. and note).
But by the endeavour to persist in its being, in so far as it is attributable to mind and body in conjunction, we mean appetite and desire (3.9. note).
Therefore pleasure and pain are identical with desire or appetite, in so far as by external causes they are increased or diminished, helped or hindered, in other words, they are every man's nature;
Wherefore the pleasure and pain felt by one man differ from the pleasure and pain felt by another man, only in so far as the nature or essence of the one man differs from the essence of the other;
Consequently, any emotion of one individual only differs, &c. Q.E.D.
Note: It follows that the emotions of the animals which are called irrational (for after learning the origin of mind we cannot doubt that brutes feel) only differ from man's emotions, to the extent that brute nature differs from human nature.
Horse and man are alike carried away by the desire of procreation; but the desire of the former is equine, the desire of the latter is human.
So also the lusts and appetites of insects, fishes, and birds must needs vary according to the several natures.
Thus, although each individual lives content and rejoices in that nature belonging to him wherein he has his being, yet the life, wherein each is content and rejoices, is nothing else but the idea, or soul, of the said individual, and hence the joy of one only differs in nature from the joy of another, to the extent that the essence of one differs from the essence of another.
Lastly, it follows from the foregoing proposition, that there is no small difference between the joy which actuates, say, a drunkard, and the joy possessed by a philosopher, as I just mention here by the way.
Thus far I have treated of the emotions attributable to man, in so far as he is passive. It remains to add a few words on those attributable to him in so far as he is active.
Proposition 58: Besides pleasure and desire, which are passivities or passions, there are other emotions derived from pleasure and desire, which are attributable to us in so far as we are active. Proof: When the mind conceives itself and its power of activity, it feels pleasure (3.53.).
Now the mind necessarily contemplates itself, when it conceives a true or adequate idea (2.43).
But the mind does conceive certain adequate ideas (2.40. note 2.).
Therefore it feels pleasure in so far as it conceives adequate ideas; that is, in so far as it is active (3.1.).
Again, the mind, both in so far as it has clear and distinct ideas, and in so far as it has confused ideas, endeavours to persist in its own being (3.9.).
But by such an endeavour we mean desire (by the note to the same Prop.).
Therefore, desire is also attributable to us, in so far as we understand, or (3.1.) in so far as we are active. Q.E.D.
Proposition 59: Among all the emotions attributable to the mind as active, there are none which cannot be referred to pleasure or desire.
Proof: All emotions can be referred to desire, pleasure, or pain, as their definitions, already given, show.
Now by pain we mean that the mind's power of thinking is diminished or checked (3.11. and note).
Therefore, in so far as the mind feels pain, its power of understanding, that is, of activity, is diminished or checked (3.1.).
Therefore, no painful emotions can be attributed to the mind in virtue of its being active, but only emotions of pleasure and desire, which (by the last Prop.) are attributable to the mind in that condition. Q.E.D.
Note: All actions following from emotion, which are attributable to the mind in virtue of its understanding, I set down to strength of character (fortitudo), which I divide into courage ( animositas) and highmindedness (generositas).
Courage means the desire to preserve one's own being rationally.
Highmindedness means the desire to aid other men and be friends with them rationally.
Those actions, therefore, which have regard solely to the good of the agent I set down to courage, those which aim at the good of others I set down to highmindedness.
Thus temperance, sobriety, and presence of mind in danger, etc., are varieties of courage; courtesy, mercy, etc., are varieties of highmindedness.
I have thus explained, and displayed through their primary causes the principal emotions and vacillations of spirit, which arise from the combination desire, pleasure, and pain.
We are in many ways driven about by external causes.
Like waves of the sea driven by contrary winds, we toss to and fro unwitting of the issue and of our fate.
I have only given the chief conflicting emotions, not all that might be given, because we can easily show that love is united to repentance, scorn, shame, etc.
Emotions may be compounded one with another in so many ways that cannot be computed.
It is enough to have enumerated the most important.
I have left the rest to those who are more curious than profitable.
Regarding love, while we are enjoying a thing which we longed for, the act of enjoyment by the body arouses other images of things that makes the mind desire them fresh.
For example, when we taste a delicious food, we desire to enjoy it, that is, to eat it.
But while we are thus enjoying it, the stomach is filled.
If the image of the food is stimulated again, it stimulates the desire to eat it also.
The new disposition of the body will feel repugnance to the desire.
Consequently the presence of the food which we formerly longed for will become odious.
This revulsion of feeling is called satiety or weariness.
For the rest, I have neglected the outward modifications of the body observable in emotions, such, for instance, as trembling, pallor, sobbing, laughter, &c.,
These are attributable to the body only, without any reference to the mind.
Lastly, the definitions of the emotions require to be supplemented in a few points;
I will therefore repeat them, interpolating such observations as I think should here and there be added.