Logos

... the universe is organized according to rational principles, the Logos. This can be interpreted as God (for instance in Epictetus), but also simply as the idea that Nature is understandable by way of rationality (which is why we can scientifically investigate it).

Stoic philosophers identified the term logos with the divine animating principle pervading the Universe… The Stoics also spoke of the logos spermatikos (the generative principle of the Universe)... Stoic philosophy began with Zeno of Citium c. 300 BC, in which the logos was the active reason pervading and animating the Universe. It was conceived as material and is usually identified with God or Nature. The Stoics also referred to the seminal logos ("logos spermatikos"), or the law of generation in the Universe, which was the principle of the active reason working in inanimate matter.

Pierre Hadot describes the Logos like this: "The immanence of reason in matter. The reason that governs substance."

David Sedley: "Stoic Chrysippus regarded pneuma as the vehicle of logos in structuring matter, both in animals and in the physical world.

Margaret Graver: "incorporates within itself a set of structural principles which are linked to the structure and organization of the universe as a whole. The universe as a whole exhibits a structural and functional complexity like that of living things."

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"The miraculous order which manifests itself in all of nature as well as in the world of ideas" Albert Einstein.

This worldview is not a pat, obvious observation. Rather, it functions as a profound recognition of the ubiquitous goodness and wisdom of the structure Marcus finds himself embedded in. The perpetual unity of the diverse elements of the cosmos reflects a simultaneous monism of divinity, substance, law, and intelligibility:

“Everything is interwoven, and the web is holy; none of its parts are unconnected. They are composed harmoniously, and together they compose the world. One world, made up of all things. One divinity, present in them all. One substance and one law — the logos that all rational beings share. And one truth. If this is indeed the culmination of one process, beings who share the same birth, the same logos”. (vii. 9; ix. 8, ix. 39)

So the logos, the coherence, order, divinity, and interconnectedness of all things in the cosmos also establish a norm, an action guiding principle, which all beings with the capacity to recognize it share in common. All rational beings share a common origin and a common birth in this unified cosmos. All rational beings share a common law by which to govern their lives together. Consequently, all rational beings, all beings with sufficient intelligence, can comprehend this one truth that they are bound together both with the cosmic whole, with each other, with all other animate inhabitants and with all inanimate components of the world.

The proper place and function of each part derives directly from its relation to the whole. The needs of the whole (the cosmos) dictate the proper course for the part (the individual person). This arrangement, Marcus, like all Stoics, takes to be providential: “What is divine is full of Providence. Even chance is not divorced from nature, from the inweaving and enfolding of things governed by Providence. Everything proceeds from it” (ii. 3). It's unclear how much room there is for chance in Marcus‟ cosmology, but here he claims that even chance fits within nature, tied into the unfolding of events in nature. He continues:

“And then there is necessity and the needs of the whole world, of which you are a part. Whatever the nature of the whole does, and whatever serves to maintain it, is good for every part of nature. The world is maintained by change—in the elements and in the things they compose. That should enough for you; treat it as an axiom”. (ii. 3)

This is a crucial inference in the logic of Marcus‟ cosmic mereology. Since the part is what it is by necessity, that is, since a part is necessarily a part of a particular whole, the good of a part must necessarily derive from the good of that whole of which it is a part.