The positive exposition of atomism has much that is attractive, but the hypothesis of the calor vitalis (vital heat), a species of anima mundi (world-soul) which is introduced as physical explanation of physical phenomena, does not seem to throw much light on the special problems which it is invoked to solve.
We have evidence that he did not substitute an immanent world-soul for Aristotle's extra-mundane deity; he recognized nothing beyond natural necessity.
In the rational creatures - man and the gods - Pneuma is manifested in a high degree of purity and intensity as an emanation from the world-soul, itself an emanation from the primary substance of purest ether - a spark of the celestial fire, or, more accurately, fiery breath, which is a mean between fire and air, characterized by vital warmth more than by dryness.
A Stoic might consistently maintain that World-Soul, Providence, Destiny and Germinal Reason are not mere synonyms, for they express different aspects of God, different relations of God to things.
He disagrees with Fechner's hypothesis of a world-soul, the highest spirit, God, who embraces all psychophysical processes.