One intelligent soul for all. An ascending gradation of ensoulment: among non-rational animals a single TERMsoul is "divided out" (διῄρηται) — one vital nature; among rational beings a single intelligent soul (μία νοερὰ ψυχή) is "parcelled out" (μεμέρισται). Marcus ranks the rational higher: what unites them is not mere life but mind. There follow three physical "ones" that prop the thought by analogy: one earth for all earthy things, one light by which all see, one air all breathe. As the body shares in common elements, so reason shares in a common rational principle.

The ground of sociability. This is not abstract cosmology but the physical basis of DOGMAoikeiōsis: if the rational soul in all is one, then another human being is literally kindred to me in mind, and enmity toward him is a split within a single thing. The thesis is carried straight on in 9.9 (all that is akin strives toward the akin) and rests on the DOGMAunity of the cosmos (cf. 12.30: "one light of the sun… one intelligent element divided among all"). The governing discipline is desire (the contemplation of nature that yields acceptance of one's place in the whole).