Book 7
1.133
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.
1.134
They hold that there are two principles in the universe, the active principle and the passive. The passive principle, then, is a substance without quality, i.e. matter, whereas the active is the reason inherent in this substance, that is God. For he is everlasting and is the artificer of each several thing throughout the whole extent of matter. This doctrine is laid down by Zeno of Citium in his treatise On Existence, Cleanthes in his work On Atoms, Chrysippus in the first book of his Physics towards the end, Archedemus in his treatise On Elements, and Posidonius in the second book of his Physical Exposition. There is a difference, according to them, between principles and elements; the former being without generation or destruction, whereas the elements are destroyed when all things are resolved into fire. Moreover, the principles are incorporeal and destitute of form, while the elements have been endowed with form.
