Now in the sixteenth book of his great work Varro co-ordinated this Stoic theory with the Graeco-Roman religion of the State as it existed in his time.

The chief gods represented the _partes mundi_ in various ways; even the difference of sex among the deities was explained by regarding male gods as emanating from the heaven and female ones from the earth, according to a familiar ancient idea of the active and passive principle in generation.

The Stoic doctrine of [Greek: daimones] was also utilised to find an explanation for semi-deities, lares, genii, etc., and thus another character of the old Italian religious mind was to be saved from contempt and oblivion.

The old Italian tendency to see the supernatural manifesting itself in many different ways expressed by adjectival titles, e.g.Mars Silvanus, Jupiter Elicius, Juno Lucina, etc., also found an explanation in Varro's doctrine; for the divine element existing in sky, earth, sea, or other parts of the _mundus_, and manifesting itself in many different forms of activity, might be thus made obvious to the ordinary human intellect without the interposition of philosophical terms.
At the head of the whole system was Jupiter, the greatest of Roman gods, whose title of Optimus Maximus might well have suggested that no other deity could occupy this place.

Without him it would have been practically impossible for Varro to carry out his difficult and perilous task.