There can be no doubt about the materialism of the Stoic teaching, although both material and spiritual attributes are ascribed to God in a way that is startling. The Heracleitan conception of fire as the primary substance is the Stoic conception of God. God is fire, air, ether, and most commonly the atmospheric currents which pervade all things. But God is also the World-soul, the World-mind, the Cosmic-reason, the universal Law, Nature, Destiny, Providence. He is a perfect, happy, and kind Being. In single statements these aspects are often combined and God is described as the Fiery Reason of the world, the Mind in matter, the reasonable Air-currents. The Stoic equation is Nature ＝ Matter ＝ Fire ＝ Reason ＝ Fate ＝ Providence ＝ God. The Stoics followed Heracleitus also in their conception of the development of the present world from the cosmic fire. “In all points of detail their views on what we call physical science are contemptible. They contained not one iota of scientific thinking.”[36] They followed Aristotle, however, in their description of the elements and their teleological arrangements. The primitive substance changes by its own inner rational law into force and matter. Force is the World-soul, the pneuma or warm breath, which pervades all things. Matter is the World-body, and is water and earth. In cosmic periods the primitive fire is destined to re-absorb the world of variety into itself and then consume it in a universal catastrophe. The most important feature in the Stoic materialism is the conception of pneuma, or the force into which the original substance is differentiated. This is the World-soul. Nature is thus conceived as dynamical. The Stoic word for the World-soul is translated by various expressions, as “creative reason,” “generative powers,” “formative fire-mind.” It penetrates all things and dominates all as their active principle. Through it the universe is one, not a plurality of parts. The pneuma is the life of the universe. Its motion is spontaneous; its development is teleological. The pneuma is an extraordinarily condensed conception, containing as it does suggestions from Heracleitus’ Logos, Anaxagoras’ Nous, Democritus’ fire-atoms, and Aristotle’s Energeia. The human being has a constitution analogous to the universe. Man is the microcosm and the universe the macrocosm. The soul of man is the pneuma which holds his body together, and it is an emanation from the divine pneuma. Mental states――thought and emotions――are air currents. Virtue is the tension of the atmospheric substance of the soul. The material, yet divine, pneuma constitutes man’s reason, causes his activities, is seated in his breast. Since the pneuma is a body, it disconnects itself from the human corpse at death, has a limited immortality, and returns to the cosmic pneuma at the conflagration of the world.