47 But if that snake was not a present deity, says my opponent, why, after its arrival, was the violence of the plague overcome, and health restored to the Roman people? We, too, on the other hand, bring forward the question, If, according to the books of the fates and the responses of the seers, the god Aesculapius was ordered to be invited to the city, that he might cause it to be safe and sound from the contagion of the plague and of pestilential diseases, and came without spurning the proposal contemptuously, as you say, changed into the form of serpents,— why has the Roman state been so often afflicted with such disasters, so often at one time and another torn, harassed, and diminished by thousands, through the destruction of its citizens times without number?
For since the god is said to have been summoned for this purpose, that he might drive away utterly all the causes by which pestilence was excited, it followed that the state should be safe, and should be always maintained free from pestilential blasts, and unharmed. But yet we see, as was said before, that it has over and over again had seasons made mournful by these diseases, and that the manly vigour of its people has been shattered and weakened by no slight losses. Where, then, was Aesculapius?
Where that deliverer promised by venerable oracles? Why, after temples were built, and shrines reared to him, did he allow a state deserving his favour to be any longer plague-stricken, when he had been summoned for this purpose, that he should cure the diseases which were raging, and not allow anything of the sort which might be dreaded to steal on them afterwards?
Source: Against the Heathen (New Advent)