There is an origin and source of virtue. There is a root of wisdom. And, there is, so to speak, a region of changeless truth. If the soul leaves this region, it lives in darkness but, when it approaches this region, it is enlightened.
(En. in ps. 58, S 1, 18)
Because every man is a neighbor to all men, one should not allow any kind of distance where there is a common nature.
(En. in ps. 118, S 8, 2)
From infancy to old age, each age in all men has its own special beauty.
(De div. quaest. LXXXIII q.44)