Augustine of Hippo
Catena Aurea · Matthäusevangelium 6
The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light. But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!
(cont. Mendac. 7.) But acts which are known to be in themselves sins, are not to be done as with a good purpose; but such works only as are either good or bad, according as the motives from which they are done are either good or bad, and are not in themselves sins; as to give food to the poor is good if it be done from merciful motives, but evil if it be done from ostentation. But such works as are in themselves sins, who will say that they are to be done with good motives, or that they are not sins? Who would say, Let us rob the rich, that we may have to give to the poor?