Lives of Eminent Philosophers 7.133 — Diogenes Laërtius on the Stoics

Diogenes Laërtius, Lives of Eminent Philosophers 7.133

Reported speech · Diogenes Laërtius on the Stoics

this includes such questions as what the substance of the universe is, whether the sun and the stars are made up of form and matter, whether the world has had a beginning in time or not, whether it is animate or inanimate, whether it is destructible or indestructible, whether it is governed by providence, and all the rest. The part concerned with causation, again, is itself subdivided into two. And in one of its aspects medical inquiries have a share in it, in so far as it involves investigation of the ruling principle of the soul and the phenomena of soul, seeds, and the like. Whereas the other part is claimed by the mathematicians also, e.g. how vision is to be explained, what causes the image on the mirror, what is the origin of clouds, thunder, rainbows, halos, comets, and the like.