Aristotle, Nicomachean Ethics
H. Rackham, Ed.

including embryos—the same faculty being present also in the fully-developed organism （this is more reasonable than to assume a different nutritive faculty in the latter）. [12] The excellence of this faculty therefore appears to be common to all animate things and not peculiar to man; for it is believed that this faculty or part of the soul is most active during sleep, but when they are asleep you cannot tell a good man from a bad one （whence the saying that for half their lives there is no difference between the happy and the miserable）. [13] This is a natural result of the fact that sleep is a cessation of the soul from the functions on which its goodness or badness depends—except that in some small degree certain of the sense-impressions may reach into soul during sleep, and consequently the dreams of the good are better than those of ordinary men. [14] We need not however pursue this subject further, but may omit from consideration the nutritive part of the soul, since it exhibits no specifically human excellence. [15]

But there also appears to be another element in the soul, which, though irrational, yet in a manner participates in rational principle. In self-restrained and unrestrained¹ people we approve their principle, or the rational part of their souls, because it urges them in the right way and exhorts them to the best course; but their nature seems also to contain another element beside that of rational principle, which combats and resists that principle. [16] Exactly the same thing may take place in the soul as occurs with the body in a case of paralysis: when the patient wills to move his limbs to the right