Abstract
The metaphysical doctrine of the Stoics is a remarkable instance of a theory that appears to be materialism, but is in truth a form of unconscious ideal-realism. It is worth while to give an exposition of it in order to show that this is really the case, and, incidentally, to explain why a materialistic philosophy seems so attractive to many minds. I will refer chiefly to the teaching of the ancient Stoics, i.e. of Zeno, Cleanthes, and Chrysippus, and also to the later doctrine of Posidonius