Material Monism
Everything that exists is ultimately material; even the soul and the logos are subtle material substances pervading reality.
Unlike Plato, Stoics were thoroughgoing materialists — even the logos, soul, and virtues are material substances of varying refinement. This monism grounds their ethics in the physical world rather than a transcendent realm, making virtue a this-worldly achievement.
The universe is a single living creature that embraces all living creatures within it.
Stoic materialism distinguishes their naturalistic ethics from Platonic idealism and anticipates aspects of modern physicalism.
Lives of Eminent Philosophers