Each of these objects let us examine in particular. That animals have feelings, and in a degree even more exquisite than ourselves, I think we have already evinced, by what we have said of the excellence of their senses relative to appetite. Like ourselves then, animals are affected by pleasure and pain; they do not know good and evil, but they feel it; what is agreeable to them is good, what is disagreeable is bad, and both are nothing more than relations, suitable, or contrary to their nature and organization. The pleasure of tickling, and the pain from a hurt, as they depend absolutely on an action more or less strong upon the nerves, which are the organs of sentiment, are alike common to man and other animals. Whatever acts softly upon these organs, is a cause of pleasure, and whatever shakes them violently, is a cause of pain. All sensations, then, are sources of pleasure, while they are moderate, and natural; but so soon as they become too strong, they produce pain, which, in a physical sense, is the extreme, rather than the opposite of pleasure. A light too bright, a fire too hot, a noise too loud, a smell too strong, coarse victuals and severe friction, excite in us disagreeable sensations; whereas a delicate colour, a moderate heat, a soft sound, a gentle perfume, a fine savour, and light touch, please and move us with delight. Every gentle application to the senses, then, is a pleasure, and every violent shock a pain; and as the causes which occasion violent, happen more rarely in Nature than those which produce mild and moderate effects; and as animals, by the exercise of their senses, acquire in a little time the habit of avoiding every thing offensive or hurtful to them, and of distinguishing, and of approaching such as are pleasing; so without doubt they enjoy more agreeable sensations than disagreeable ones, and the amount of their pleasures exceed the amount of their pain. In man, physical pleasure and pain form the smallest part of his sufferings or enjoyments. His imagination, never idle, seems perpetually employed to increase his misery; presenting to the mind nothing but vain phantoms, or exaggerated images. More agitated by these illusions, than by real objects, the mind loses its faculty of judging, and even its dominion; the will, of which it has no longer the command, becomes a burthen; its extravagant desires are sorrows; and, at best, its prospects are delusive pleasures, which vanish as soon as the mind, resuming its place, is enabled to form a judgment of them.