But moving on from this, they try again to criticize our account by other arguments and say, 'If what happened was good and fitting for God, why did He delay the benefit? Why did He not cut short the further advance of evil when it was still at its beginnings?' Our answer to this is brief: the delay in bringing us the benefit came from wisdom and from providential concern for what would be advantageous to our nature.
For in bodily diseases, when some corrupted humor spreads beneath the pores, those who treat diseases according to their art do not administer medicines that harden the body before everything unnatural lying within has been brought out to the surface. Instead, they wait until everything hidden deep inside has come out, and then, when the disease is exposed, they apply the treatment. So, once the disease of evil had settled upon human nature, the Healer of the whole waited until no form of wickedness remained hidden in that nature.
For this reason He did not bring the remedy to humanity immediately after Cain's envy and murder of his brother. The wickedness of those destroyed in the days of Noah had not yet broken out; the grievous disease of Sodomite lawlessness had not yet been revealed; nor had the Egyptians' war against God, the Assyrians' arrogance, the Jews' bloodshed against the saints of God, or Herod's unlawful murder of the children yet appeared. Nor had all the other evils yet been committed—both those remembered in the histories and those done outside the historical record in the generations that followed—as the root of evil sprouted in many ways in the moral choices of human beings.
When, then, evil had reached its highest measure and there was no form of wickedness that human beings had not dared to attempt, the treatment could pass through the whole disease. For this reason He treats the disease not while it is beginning, but when it has reached full development.