Book 1
11
Of the irrational part of the soul again one division appears to be common to all living things, and of a vegetative nature: I refer to the part that causes nutrition and growth; for we must assume that a vital faculty of this nature exists in all things that assimilate nourishment, 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.
