[Philoponus says] that it is said that animals have their head in the upper part [sc. of their body], not at all with reference to the sky[1] surrounding them, but [thinking of] where the movement has its origin. And although most of the irrational animals -- almost all of them -- on earth are bowed forward, so that their head does not tower upon the back parts, yet it is said that the head and the regions near the head are the upper part of the animal's body. However, in the case of plants,[2] with reference to the sky, one might say that their upper parts are the branches and leaves, but with reference to the origin of movement -- and this is more natural -- the upper parts consist in the roots, the lower in the branches. For this reason, the roots are assimilated to the head and especially to the mouth, for it is through the roots, as through a mouth, that food is ministered and distributed to the body.