Timaeus

This, and such like, are just what the revolutions of the Soul experience with intensity; and every time they happen upon any external object, whether it be of the class of the Same or of the Other, they proclaim it to be the same as something or other than something contrary to the truth, and thereby prove themselves false and foolish, and devoid, at such times, of any revolution that rules and guides. And whenever external sensations in their movement collide with these revolutions and sweep along with them also the whole vessel of the Soul, then the revolutions, though actually mastered, appear to have the mastery. Hence it comes about that, because of all these affections, now as in the beginning, so often as the Soul is bound within a mortal body it becomes at the first irrational. But as soon as the stream of increase and nutriment enters in less volume, and the revolutions calm down and pursue their own path, becoming more stable as time proceeds, then at length, as the several circles move each according to its natural track, their revolutions are straightened out and they announce the Same and the Other aright, and thereby they render their possessor intelligent. And if so be that this state of his soul be reinforced by right educational training, the man becomes wholly sound and faultless, having escaped the worst of maladies; but if he has been wholly negligent therein, after passing a lame existence in life he returns again unperfected and unreasoning to Hades. These results, however, come about at a later time. Regarding the subjects now before us, we must give a more exact exposition; and also regarding the subjects anterior to these, namely, the generation of bodies in their several parts, and the causes and divine counsels whereby the Soul has come into existence, we must hold fast to the most probable account, and proceed accordingly, in the exposition now to be given. The divine revolutions, which are two, they bound within a sphere-shaped body, in imitation of the spherical form of the All, which body we now call the head, it being the most divine part and reigning over all the parts within us. To it the gods delivered over the whole of the body they had assembled to be its servant, having formed the notion that it should partake in all the motions which were to be. In order, then, that it should not go rolling upon the earth, which has all manner of heights and hollows, and be at a loss how to climb over the one and climb out of the other, they bestowed upon it the body as a vehicle and means of transport.