Sin is to a nature what blindness is to an eye. The blindness of an evil or defect which is a witness to the fact that the eye was created to see the light and, hence, the very lack of sight is the proof that the eye was meant... to be the one particularly capable of seeing the light. Were it not for this capacity, there would be no reason to think of blindness as a misforture.
Saint AugustineMen go forth to marvel at the height of mountains, and the huge waves of the sea, the broad flow of the rivers, the vastness of the ocean, the orbits of the stars, and yet they neglect to marvel at themselves. Variant: Men go abroad to admire the heights of mountains, the mighty billows of the sea, the broad tides of rivers, the compass of the ocean, and the circuits of the stars, and pass themselves by.
Saint AugustineGod suffers not the pain of repentance, nor is He deceived in any matter, so that He would wish to correct that wherein He has erred. But as when a man repents of anything, he wishes to change what he has done; thus where you hear that God repents, look for an actual change. God does it differently from you, although He calls it by the name of repentance; for thou dost it, because you had erred; while He does it, because He avenges, or frees.
Saint Augustine