Plato Timaeus 73

Those who were constructing our kind were aware of the incontinence that would reside in us in respect of drinks and meats, and how that because of our greed we would consume far more than what was moderate and necessary; wherefore, lest owing to maladies swift destruction should overtake them, 73a and the mortal kind, while still incomplete, come straightway to a complete end,—foreseeing this, the Gods set the abdomen, ¹ as it is called, to serve as a receptacle for the holding of the superfluous meat and drink; and round about therein they coiled the structure of the entrails, to prevent the food from passing through quickly and thereby compelling the body to require more food quickly, and causing insatiate appetite, whereby the whole kind by reason of its gluttony would be rendered devoid of philosophy and of culture, and disobedient to the most divine part we possess.
  As regards the bones and the flesh and all such substances 73b the position was this. All these had their origin in the generation of the marrow. For it was in this that the bonds of life by which the Soul is bound to the body were fastened, and implanted the roots of the mortal kind; but the marrow itself was generated out of other elements. Taking all these primary triangles ² which, being unwarped and smooth, were best able to produce with exactness fire and water and air and earth, God separated them, each apart from his own kind, 73c and mixing them one with another in due proportion, He fashioned therefrom the marrow, devising it as a universal seed-stuff for every mortal kind. Next, He engendered therein the various kinds of Soul ³ and bound them down; and He straightway divided the marrow itself, in His original division, into shapes corresponding in their number and their nature to the number and the nature of the shapes which should belong to the several kinds of Soul. And that portion of the marrow which was intended to receive within itself, as it were into a field, the divine seed He molded 73d in the shape of a perfect globe ⁴ and bestowed on it the name of brain, purposing that, when each living creature should be completed, the vessel surrounding this should be called the head. But that portion which was to contain the other and mortal part of the Soul He divided into shapes that were at once rounded and elongated, ⁵ and all these He designated marrow; and from these, as from anchors, He cast out bands of the Whole Soul, and around this He finally wrought the whole of this body of ours, when He had first built round about it for a shelter a framework 73e all of bone.
  And bone He compounded in this wise. Having sifted earth till it was pure and smooth, He kneaded it and moistened it with marrow; then He placed it in fire, and after that dipped it in water, and from this back to fire, and once again in water; and by thus transferring it many times from the one element to the other He made it so that it was soluble by neither.