Affection may be generally understood as the impression people around us or within us leave on our soul/spirit. Affection , however, is more commonly understood as an intense feeling of pleasure or aversion in us, regardless of the cause. For example, a painting representing things in nature that offend our senses is said to affect us negatively. Similarly, a heroic action or the story related to it is said to affect us delightfully.

Such is our constitution that in this state in which one feels love or hate, or attraction or aversion, muscles move in the body and dictate the intensity or the withdrawal of these feelings. Joy never surges without a great dilation and palpitation of the heart, the quickening of the pulse, until it becomes aware of its own condition; perspiration then becomes so strong that one could faint or even die. Anger stops or increases all movements, in particular the circulation of the blood; which makes the body hot, red, and trembling, etc... but it is evident that these symptoms will be more or less violent depending on the disposition of the parts and mechanisms of the body.

This physical mechanism is rarely such that freedom of the soul is suspended throughout these impressions. There is no doubt, however, that this sometimes happens; it is within this mechanism of the body that one must search for the cause of differing sensitivities of different men, occasionally towards the same object. We are like musical instruments whose strings are of various tensions; the exterior objects function as bows on these strings, and bring from all of us sounds that are more or less sharp. The prick of a pin makes women raised gently scream; the strike of a baton breaks the leg of Epictetus almost without moving him. Our constitution, our education, our principles, our systems, our prejudices, all modify our affections and the movements of the body that follow them. The start of affection can be so sharp, that the Law which initially defines it as the first reaction treats its effects simply as reflexes [ des actes non libres ]. It is evident, however, based on what we just described, that the first movement lasts more or less depending on the differences in constitutions, and on an infinite number of other circumstances. We would thus do well to reserve judgment on actions brought about by violent passions. It is preferable to be too indulgent than too severe, to assume weakness rather than cruelty in men, and to be able to bring one’s wariness to bear on the first of these feelings rather than the second. We pity the weak, we hate the cruel, and it seems to me that commiseration is preferable to hatred.