Aristotle On Youth and Old Age,On Life and Death,On Breathing-Part 1

WE must now treat of youth and old age and life and death. We mustprobably also at the same time state the causes of respiration aswell, since in some cases living and the reverse depend on this.We have elsewhere given a precise account of the soul, and whileit is clear that its essential reality cannot be corporeal, yetmanifestly it must exist in some bodily part which must be one ofthose possessing control over the members. Let us for the presentset aside the other divisions or faculties of the soul (whichever ofthe two be the correct name). But as to being what is called an animaland a living thing, we find that in all beings endowed with bothcharacteristics (viz. being an animal and being alive) there must be asingle identical part in virtue of which they live and are calledanimals; for an animal qua animal cannot avoid being alive. But athing need not, though alive, be animal, for plants live withouthaving sensation, and it is by sensation that we distinguish animalfrom what is not animal.This organ, then, must be numerically one and the same and yetpossess multiple and disparate aspects, for being animal and livingare not identical. Since then the organs of special sensation have onecommon organ in which the senses when functioning must meet, andthis must be situated midway between what is called before andbehind (we call 'before' the direction from which sensation comes,'behind' the opposite), further, since in all living things the bodyis divided into upper and lower (they all have upper and lowerparts, so that this is true of plants as well), clearly thenutritive principle must be situated midway between these regions.That part where food enters we call upper, considering it by itselfand not relatively to the surrounding universe, while downward is thatpart by which the primary excrement is discharged.Plants are the reverse of animals in this respect. To man inparticular among the animals, on account of his erect stature, belongsthe characteristic of having his upper parts pointing upwards in thesense in which that applies to the universe, while in the others theseare in an intermediate position. But in plants, owing to their beingstationary and drawing their sustenance from the ground, the upperpart must always be down; for there is a correspondence between theroots in a plant and what is called the mouth in animals, by meansof which they take in their food, whether the source of supply bethe earth or each other's bodies.