It is manifest that an animal body cannot be simple, cannot, I mean, be only fire or air; for an animal cannot have any other sense without having Touch, and every living body is sensible to Touch, as has been said. But all the elements, except earth, may constitute sentient organs, as these all receive impressions through something foreign to themselves and through media; but the Touch is made sensible by touching bodies, and hence its name. And yet the other sentient organs do perceive by Touch, but then it is through something foreign to themselves; while Touch alone seems to perceive directly, through itself. So that an animal body cannot be constituted of any one of the other elements exclusively, nor can it be formed only of earth; for the Touch is the medium, as it were, for tangible impressions, and the organ is perceptive not only of the distinctions which pertain to earth, but of hot, cold, and all other tangible qualities. Hence it is that we have no feeling in bones, hair, or other analogous parts because they are of earth; and plants for the same reason, being of earth have no feeling. It is impossible then that there should be any other sense without that of Touch; and its organ is neither of earth nor any other element exclusively. Thus, it is manifest that the Touch is the only sense of which animals cannot be deprived without dying; that animals only can possess it; and that it alone of the senses is necessary to animal existence. On which account, other sentient impressions in excess (as those of colour, sound and odour) may injure the organs but do not destroy the animal, excepting it be by chance, as when with sound there is an impulse and a blow, or as when, by visual or odorous impressions, other influences are set in motion, which destroy the animal through the Touch and when savour destroys life it does so by communicating simultaneously a tangible impression. But the excess of tangible impression, whether hot, cold or hard, destroys the animal, because as every impression in excess destroys the sentient organ, so the tangible destroys that of Touch, and it is by the Touch that animal life has been defined; and it has been shewn that an animal cannot possibly exist without the Touch. Thus, the excess of tangible impressions destroys not the organ only but the animal, as that sense alone is necessary to its existence. Animals, in fact, possess, as has been said, the other senses, not merely for existence but, for higher enjoyment: they have sight, in order that, as they live in air and water, in a transparent medium in short, they may see; taste, that by discerning what is grateful or nauseous in food they may have desire for and move to obtain it; hearing, that others may signify something to them, and a tongue that they may signify something to others.