John Chrysostom : The fact, too, that he brought on the deluge for forty days and nights is a further wonderful sign of his loving kindness. His purpose in his great goodness was that at least some of them might come to their senses and escape that utter ruin, having before their eyes the annihilation of their peers and the destruction about to overwhelm them. I mean, the likelihood is that on the first day some proportion were drowned, an additional number on the second day, and likewise on the third day and so on. His reason for extending it for forty days was that he might remove from them any grounds for excuse. You see, had it been his wish and command, he could have submerged everything in one downpour. Instead, out of fidelity to his characteristic love he arranged for a stay of so many days. — HOMILIES ON Genesis 25.11