In Plato’s dialogue the Timaeus, the title character Timaeus of Locri gives a long speech in which he speculates about how the universe, which is as good as possible, got created by a benevolent Demiurge. Timaeus says: “…we may say that the world became a living creature truly endowed with soul and intelligence by the providence of God.”
The conception of the world as a living creature with divine soul and intelligence probably originated between the fifteenth and ninth centuries BC—the Rigveda has several hymns which proclaim that the universe is a manifestation of the One, the omnipotent and omnipresent Paramatman, who is the great soul and living principle, that is the undivided, timeless, and motionless author of everything. The hymn 72 in Mandala 10 talks about the birth of the gods and the heavenly bodies of the universe from the One (translations by Stephanie W. Jamison and Joel P. Brereton, OUP, 2014):
1. Now amid acclaim we will proclaim the births of the gods,
so that one in a later generation will see (them) as the hymns are recited.
2. The Lord of the Sacred Formulation [=Bṛhaspati] smelted these (births) like a smith.
In the ancient generation of the gods, what exists was born from what does not exist.
3. In the first generation of the gods, what exists was born from what does not exist.
The regions of space were born following that (which exists)—that (which exists) was born from the one whose feet were opened up.
4. The earth was born from the one whose feet were opened up; from the earth the regions of space were born.
From Aditi, Dakṣa was born, and from Dakṣa, Aditi.
5. Because Aditi was born—she who is your daughter, o Dakṣa— following her, the gods were born, the auspicious kin of the immortal one.
6. When, o gods, well clasped to one another, you stood there in the ocean, then the bitter dust [=spray] dispersed from you, like (the dust [=sweat?]) of those dancing.
7. When, o gods, just as the Yatis did, you swelled the living worlds, then you brought here the sun, which was hidden in the sea.
8. Eight are the sons of Aditi, which were born from her body.
With seven she went forth to the gods. She cast away the one stemming from a dead egg.
9. With seven sons Aditi went forth to the ancient generation.
For procreation but also for death, she brought here again the one stemming from a dead egg.
Monism is also apparent in the verse 46 of hymn 164 in Mandala 1:
They say it is Indra, Mitra, Varuṇa, and Agni, and also it is the winged, well-feathered (bird) of heaven [=the Sun].
Though it is One, inspired poets speak of it in many ways. They say it is Agni, Yama, and Mātariśvan.