Meditations

Upon this the senses write their impressions, fantasias and by experience of a number of these the soul unconsciously conceives general notions koinai eunoiai or anticipations. prolhyeis When the impression was such as to be irresistible it was called (katalnptikh fantasia) one that holds fast, or as they explained it, one proceeding from truth.

This dictum might easily be taken to mean that virtue consists in yielding to each natural impulse; but that was very far from the Stoic meaning. In order to live in accord with nature, it is necessary to know what nature is; and to this end a threefold division of philosophy is made—into Physics, dealing with the universe and its laws, the problems of divine government and teleology; Logic, which trains the mind to discern true from false; and Ethics, which applies the knowledge thus gained and tested to practical life. The Stoic system of physics was materialism with an infusion of pantheism. In contradiction to Plato's view that the Ideas, or Prototypes, of phenomena alone really exist, the Stoics held that material objects alone existed; but immanent in the material universe was a spiritual force which acted through them, manifesting itself under many forms, as fire, aether

This conforming of the life to nature oralogoumenwz th fusei zhn. was the Stoic idea of Virtue.