29 We might, however, even yet be able to receive from you these thoughts, most full of wicked falsehoods, if it were not that you yourselves, in bringing forward many things about the gods so inconsistent and mutually destructive, compel us to withhold our minds from assenting. For when you strive individually to excel each other in reputation for more recondite knowledge, you both overthrow the very gods in whom you believe, and replace them by others who have clearly no existence; and different men give different opinions on the same subjects, and you write that those whom general consent has ever received as single persons are infinite in number.
Let us, too, begin duty, then, with father Janus, whom certain of you have declared to be the world, others the year, some the sun. But if we are to believe that this is true, it follows as a consequence, that it should be understood that there never was any Janus, who, they say, being sprung from Coelus and Hecate, reigned first in Italy, founded the town Janiculum, was the father of Forts, the son-in-law of Vulturnus, the husband of Juturna; and thus you erase the name of the god to whom in all prayers you give the first place, and whom you believe to procure for you a hearing from the gods.
But, again, if Janus be the year, neither thus can he be a god. For who does not know that the year is a fixed space of time, and that there is nothing divine in that which is formed by the duration of months and lapse of days? Now this very argument may, in like manner, be applied to Saturn. For if time is meant under this title, as the expounders of Grecian ideas think, so that that is regarded as Kronos, which is chronos, there is no such deity as Saturn. For who is so senseless as to say that time is a god, when it is but a certain space measured off in the unending succession of eternity?
And thus will be removed from the rank of the immortals that deity too, whom the men of old declared, and handed down to their posterity, to be born of father Coelus, the progenitor of the dii magni, the planter of the vine, the bearer of the pruning-knife.
Source: Against the Heathen (New Advent)