Cleanthes of Assos (342-232 BC) was a philosopher and poet, who headed the Stoa from 262 BC onwards, after Zeno (its founder) died. He introduced a theological motif to Stoicism by articulating the cosmology of his predecessors with passionate, but contemplative, religiosity. Cleanthes encapsulated his awe of the universal law in Hymn to Zeus. For instance, he reverentially intones Zeus, “the First Cause of Nature, who rules all things with Law, Hail!” This work was so influential that antiquity felt a deep responsibility to preserve it. Although Cleanthes was an innovative philosopher, however, contemporaries deemed him an obtuse learner, who lacked the mental adroitness required for adjudicating intricate logical problemata.
Anaximenes of Miletus (fl. c. 546-525 BC), on the other hand, was a Presocratic thinker best known for postulating air as the primordial cosmic substrate. He was both a noted physiologist (= natural philosopher) and monist, who along with Cleanthes averred that air “is the chief deity.” Referring to Cleanthes’ and Anaximenes' respective theories of air, Lactantius relates: “to this opinion our poet [Virgil] has assented: ‘Then almighty father Aether descends in fertile showers into the bosom of his joyous wife, mingling his greatness in her great body and nourishing all her children.’”
 See Copleston, History of Philosophy, 385.
 Colish, The Stoic Tradition, 1:10.
 Hymn to Zeus, M.A.C. Ellery translation. Quoted in Manson 91.
 See Everett Ferguson, Backgrounds of Early Christianity (Eerdmans: 2003), 355.
 See Bowen and Garnsey, Divine Institutes, 67.
 DI 1.5.19. See Virgil’s Georgics 2.325-327. In the same work, the poet calls Bacchus, the “Father of the winepress.” The actual lines from Virgil read: “In Spring earth swells and claims the fruitful seed. The Aether, Sire [Father] omnipotent, leaps down with quickening showers to his glad wife’s embrace, And might with might commingling, rears to life all germs that teem within her.” Other passages where the poet mentions divine fathers are Aeneid 1.50: “In fear of this, the Father of the gods, Confin’d their fury to those dark abodes . . .” and 1.142ff: “the Father of the flood.” See 1.223: “To whom the Father of the human race, Smiling with that serene indulgent face . . .” (1.254) Cf. Aeneid 8: “Arose the father of the Roman flood.” Finally, in Aeneid 8, Virgil alludes to “Father Tiber.”