The Stoics believed the whole cosmos to be God which directs all things along their determined paths. The Stoics believed the universe to be composed of an active and creative fire or breath (pneuma) that was coextensive with passive matter (ousia). Pneuma is like a field that emanates through all the ousia and gives ousia its stable physical form.
Richard Feynman believed that electromagnetic fields, which could be likened to the Stoic concept of pneuma, are real and existing fields that have their own energy.
“The fact that the electromagnetic field can possess momentum and energy makes it very real … a particle makes a field, and a field acts on another particle, and the field has such familiar properties as energy content and momentum, just as particles can have.”Richard P. Feynman (1970). The Feynman Lectures on Physics Vol I. Addison Wesley Longman.
So pneuma could be rightly thought of as a field that emanates through all of passive matter throughout the universe and help give it stable properties. Pneuma can create the conditions for life, sensations, and then rational self-awareness.
There’s been this belief that the Stoics have committed a fallacy of composition by regarding the universe as both good and rational. But they were careful to distinguish properties of objects and events from the whole body of objects and events. The Stoics described events, objects, and things like wealth, health, pain, pleasure, a stormy night, a beautiful sunset as neither good nor bad. But they claimed that the universe, the complete picture, or all of the events as one whole thing is good or is rational. This is clearly not a fallacy of composition.
The Stoics believed that the universe was good and rational because it had made a world of rational beings. Also, the planets, moon, and the sun all appear to move in an ordered rational manner. The tides went in and the tide went out. Everything as far as they could see was rational and well ordered from the smallest to the largest scales. That’s not a fallacy of composition, that is a fact. Even today in modern physics, there are rational laws from the tiniest particles to the largest superclusters of galaxies.
The Stoics did not believe that the universe is like any organism on Earth. But they did believe it was alive and rational and good because it at least created humans which are also capable of using reason. The universe appears to act in accordance with itself the way that we should also act in accord with ourselves. Everything that the universe does and creates, we should want. That doesn’t mean we should allow vicious people on Earth to do vicious things. We should obviously stand against injustice but while acknowledging that everything unfolds from a blueprint that acts through every concurrent sets of events.
So, again, the Stoics did not commit any fallacy of composition with regard to thinking of the universe as rational or good. Instead, they noticed that everything happened in a lawlike way on every scale, just like we should regulate ourselves and become virtuous Sages.