We call a thing good which contributes to the preservation of our being, and we call a thing evil if it is an obstacle to the preservation of our being; that is to say, a thing is called by us good or evil as it increases or diminishes, helps or restrains, our power of action. In so far, therefore, as we perceive that any object affects us with joy or sorrow do we call it good or evil, and therefore the knowledge of good or evil is nothing but an idea of joy or sorrow which necessarily follows from the emotion itself of joy or sorrow. But this idea is united to the emotion in the same way as the mind is united to the body, or, in other words, this idea is not actually distinguished from the emotion itself; that is to say, it is not actually distinguished from the idea of the modification of the body, unless in conception alone. This knowledge, therefore, of good and evil is nothing but the emotion itself of joy and sorrow in so far as we are conscious of it.
The Control of the Emotions
An emotion, in so far as it is related to the mind, is an idea by which the mind affirms a greater or less power of existence for its body than the body possessed before. Whenever, therefore, the mind is agitated by any emotion, the body is at the same time affected with a modification by which its power of action is increased or diminished. Again, this modification of the body receives from its own cause a power to persevere in its own being, a power, therefore, which cannot be restrained nor removed unless by a bodily cause affecting the body with a modification contrary to the first, and stronger than it. Thus the mind is affected by the idea of a modification stronger than the former and contrary to it; that is to say, it will be affected with an emotion stronger than the former and contrary to it, and this stronger emotion will exclude the existence of the other or remove it. Thus an emotion cannot be restrained nor removed unless by an opposed and stronger emotion.
An emotion, in so far as it is related to the mind, cannot be restrained nor removed unless by the idea of a bodily modification opposed to that which we suffer and stronger than it. For the emotion which we suffer cannot be restrained nor removed unless by an opposed and stronger emotion; that is to say, it cannot be removed unless by the idea of a bodily modification stronger than that which affects us, and opposed to it.
The force and increase of any passion and its perseverance in existence are limited by the power of an external cause compared with our own power and therefore the other actions or power of a man may be so far surpassed by force of some passion or emotion, that the emotion may obstinately cling to him.
An emotion is an idea by which the mind affirms a greater or less power of existence for the body than it possessed before, and therefore this idea has nothing positive which can be removed by the presence of the truth, and consequently the true knowledge of good and evil, in so far as it is true, can restrain no emotion. But in so far as it is an emotion will it restrain any other emotion, provided that the latter be the weaker of the two.
From the true knowledge of good and evil, in so far as this is an emotion, necessarily arises desire, which is greater in proportion as the emotion from which it springs is greater. But this desire (by hypothesis), because it springs from our understanding, something truly follows therefore in us in so far as we act, and therefore must be understood through our essence alone, and consequently its strength and increase must be limited by human power alone. But the desires which spring from the emotions by which we are agitated are greater as the emotions themselves are greater, and therefore their strength and increase must be limited by the power of external causes, a power which, if it be compared with our own, indefinitely surpasses it. The desires, therefore, which take their origin from such emotions as these may be much stronger than that which takes its origin from a true knowledge of good and evil, and the former may be able to restrain and extinguish the latter.
Desire is the very essence of man, that is to say, the effort by which a man strives to persevere in his being. The desire, therefore, which springs from joy, by that very emotion of joy is assisted or increased, while that which springs from sorrow, by that very emotion of sorrow is lessened or restrained, and so the force of the desire which springs from joy must be limited by human power, together with the power of an external cause, while that which springs from sorrow must be limited by human power alone. The latter is, therefore, weaker than the former.