The most irrational theory of all is that an aggregation of molecules
should produce life, that elements without intelligence should beget
intelligence. Others (like Alexander of Aphrodisia) insist that to
produce life these elements must be mingled in a certain manner. That
would, however, imply (as thought Gallen and Hippocrates[38]) the
existence of a principle which produces order, and which should be the
cause of mixture or, temperament,[39] and that should alone deserve
being considered as soul. No simple bodies could exist, much less
composite bodies, unless there was a soul in the universe; for it is
(seminal) reason which, in, adding itself to matter, produces body.[40]
But surely a (seminal) reason could proceed from nowhere except a soul.