motion. This appears by the way whereby heat is produced; for we see that the rubbing of a brass nail upon a board will make it very hot; and the axle-trees of carts and coaches are often hot, and sometimes to a degree, that it sets them on fire, by the rubbing of the nave of the wheel upon it.
On the other side, the utmost degree of cold is the cessation of that motion of the insensible particles, which to our touch is heat.
Bodies are denominated hot and cold in proportion to the present temperament of that part of our body to which they are applied; so that feels hot to one, which seems cold to another; nay, the same body, felt by the two hands of the same man, may at the same time appear hot to the one, and cold to the other; because the motion of the insensible particles of it may be more brisk than that of the particles of the other.
Besides the objects before-mentioned, which are peculiar to each of our senses, as light and colour of the sight; sound of hearing; odours of smelling; savours of tasting; and tangible qualities of the touch; there are two others that are common to all the senses; and those are pleasure and pain, which they may receive by and with their peculiar objects. Thus, too much light offends the eye; some sounds delight, and others grate the ear; heat in a certain degree is very pleasant, which may be augmented to the greatest torment; and so the rest.
These five senses are common to beasts with men; nay, in some of them, some brutes exceed mankind. But men are endowed with other faculties, which far excel any thing that is to be found in the other animals in this our globe.
Memory also brutes may be supposed to have, as well as men.
