Next to this comes the life of sense; but this too he plainly shares with horses and cattle and all kinds of animals.

There remains then the life whereby he acts⁠—the life of his rational nature, 11 with its two sides or divisions, one rational as obeying reason, the other rational as having and exercising reason.

But as this expression is ambiguous, 12 we must be understood to mean thereby the life that consists in the exercise of the faculties; for this seems to be more properly entitled to the name.

The function of man, then, is exercise of his vital faculties [or soul] on one side in obedience to reason, and on the other side with reason.