Pseudo-Chrysostom
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!
It seems that He is not here speaking of the bodily eye, or of the outward body that is seen, or He would have said, If thine eye be sound, or weak; but He says, single, and, evil. But if one have a benign yet diseased eye, is his body therefore in light? Or if an evil yet a sound, is his body therefore in darkness?