Propositions 14 to 19

14. A true knowledge of good and evil cannot check any emotion by virtue of being true, but only in so far as it is considered as an emotion.

Proof: An emotion is an idea, whereby the mind affirms of its body a greater or less force of existing than before (by the general Definition of the Emotions).

Therefore, it has no positive quality, which can be destroyed by the presence of what is true.

Consequently, the knowledge of good and evil cannot, by virtue of being true, restrain any emotion.

But, in so far as such knowledge is an emotion (4.8.) if it have more strength for restraining emotion, it will to that extent be able to restrain the given emotion. Q.E.D.

15. Desire arising from the knowledge of good and bad can be quenched or checked by many of the other desires arising from the emotions whereby we are assailed.

Proof: From the true knowledge of good and evil, in so far as it is an emotion, necessarily arises desire (Def. of the Emotions, 1), the strength of which is proportioned to the strength of the emotion wherefrom it arises (3.37).

But, inasmuch as this desire arises (by hypothesis) from the fact of our truly understanding anything, it follows that it is also present with us, in so far as we are active (3.1.), and must therefore be understood through our essence only (3. Def. 2); Consequently (3.7.) its force and increase can be defined solely by human power.

Again, the desires arising from the emotions whereby we are assailed are stronger, in proportion as the said emotions are more vehement.

Wherefore their force and increase must be defined solely by the power of external causes, which, when compared with our own power, indefinitely surpass it (4.3.).

Hence the desires arising from like emotions may be more vehement, than the desire which arises from a true knowledge of good and evil, and may, consequently, control or quench it. Q.E.D.

16. Desire arising from the knowledge of good and evil, in so far as such knowledge regards what is future, may be more easily controlled or quenched, than the desire for what is agreeable at the present moment.

Proof: Emotion towards a thing, which we conceive as future, is fainter than emotion towards a thing that is present (4.9. Coroll.).

But desire, which arises from the true knowledge of good and evil, though it be concerned with things which are good at the moment, can be quenched or controlled by any headstrong desire (by the last Prop., the proof whereof is of universal application).

Wherefore desire arising from such knowledge, when concerned with the future, can be more easily controlled or quenched, &c. Q.E.D.

17. Desire arising from the true knowledge of good and evil, in so far as such knowledge is concerned with what is contingent, can be controlled far more easily still, than desire for things that are present.

Proof: This Prop. is proved in the same way as the last Prop. from 4.12. Coroll.

Note: I think I have now shown the reason, why men are moved by opinion more readily than by true reason, why it is that the true knowledge of good and evil stirs up conflicts in the soul, and often yields to every kind of passion. This state of things gave rise to the exclamation of the poet= [12] “The better path I gaze at and approve, The worse—I follow.”

Ecclesiastes seems to have had the same thought in his mind, when he says, “He who increaseth knowledge increaseth sorrow.” I have not written the above with the object of drawing the conclusion, that ignorance is more excellent than knowledge, or that a wise man is on a par with a fool in controlling his emotions, but because it is necessary to know the power and the infirmity of our nature, before we can determine what reason can do in restraining the emotions, and what is beyond her power. In the present part, I shall merely treat of human infirmity.

The power of reason over the emotions I have settled to treat separately.

18. Desire arising from pleasure is, other conditions being equal, stronger than desire arising from pain.

Proof: Desire is the essence of a man (Def. of the Emotions, 1), that is, the endeavour whereby a man endeavours to persist in his own being.

Wherefore desire arising from pleasure is, by the fact of pleasure being felt, increased or helped; on the contrary, desire arising from pain is, by the fact of pain being felt, diminished or hindered.

Hence the force of desire arising from pleasure must be defined by human power together with the power of an external cause, whereas desire arising from pain must be defined by human power only.

Thus the former is the stronger of the two. Q.E.D.

Note: In these few remarks I have explained the causes of human infirmity and inconstancy, and shown why men do not abide by the precepts of reason.

What course is marked out for us by reason, which of the emotions are in harmony with the rules of human reason, and which of them are contrary thereto?

But, before I begin to prove my Propositions in detailed geometrical fashion, it is advisable to sketch them briefly in advance, so that everyone may more readily grasp my meaning.

As reason makes no demands contrary to nature, it demands, that every man should love himself, should seek that which is useful to him—I mean, that which is really useful to him, should desire everything which really brings man to greater perfection, and should, each for himself, endeavour as far as he can to preserve his own being. This is as necessarily true, as that a whole is greater than its part. (Cf. 3.4)

Virtue is action in accordance with the laws of one’s own nature (4. Def. 8).

Each person’s self-preservation is based on the laws of his own nature.

It follows:

1. The foundation of virtue is self-preservation

Thereore, happiness is in man’s power of self-preservation.

2. Virtue is to be desired for its own sake

3. Suicides are weak—minded

These are overcome by external causes repugnant to their nature.

Further, it follows from Postulate 4, Part 2, that we can never arrive at doing without all external things for the preservation of our being or living, so as to have no relations with things which are outside ourselves.

Again, if we consider our mind, we see that our intellect would be more imperfect, if mind were alone, and could understand nothing besides itself.

There are, then, many things outside ourselves, which are useful to us, and are, therefore, to be desired.

Of such none can be discerned more excellent, than those which are in entire agreement with our nature.

For if, for example, two individuals of entirely the same nature are united, they form a combination twice as powerful as either of them singly.

Therefore, to man there is nothing more useful than man—nothing more excellent for preserving their being can be wished for by men, than that all should so in all points agree, that the minds and bodies of all should form, as it were, one single mind and one single body, and that all should, with one consent, as far as they are able, endeavour to preserve their being, and all with one consent seek what is useful to them all.

Hence, men who are governed by reason—that is, who seek what is useful to them in accordance with reason, desire for themselves nothing, which they do not also desire for the rest of mankind, and, consequently, are just, faithful, and honourable in their conduct.

Such are the dictates of reason, which I purposed thus briefly to indicate, before beginning to prove them in greater detail. I have taken this course, in order, if possible, to gain the attention of those who believe, that the principle that every man is bound to seek what is useful for himself is the foundation of impiety, rather than of piety and virtue.

Therefore, after briefly showing that the contrary is the case, I go on to prove it by the same method, as that whereby I have hitherto proceeded.

19. Every man, by the laws of his nature, necessarily desires or shrinks from that which he deems to be good or bad.

Proof: The knowledge of good and evil is (4.8) the emotion of pleasure or pain, in so far as we are conscious thereof; Therefore, every man necessarily desires what he thinks good, and shrinks from what he thinks bad.

Now this appetite is nothing else but man’s nature or essence (Cf. the Definition of Appetite, 3.9. note, and Def. of the Emotions, 1).

Therefore, every man, solely by the laws of his nature, desires the one, and shrinks from the other, etc. Q.E.D.