And he took unto him all these, and divided them in the midst, and laid each piece one against another: but the birds divided he not.
All Commentaries on Genesis 15:10 Go To Genesis 15
Augustine of Hippo
AD 430
And it is said, “But the birds divided he not,” because carnal people are divided among themselves. But those who are spiritual are not divided at all, whether they seclude themselves from the busy conversation of humankind, like the turtledove, or dwell among them, like the pigeon. For both birds are simple and harmless, signifying that even in the Israelite people, to which that land was to be given, there would be individuals who were children of the promise and heirs of the kingdom that is to remain in eternal felicity.