The eye of flesh is the mirror of the inward eye. The body also has its own sense, that is, the left eye, and its own appetite, that is, the left hand. But the parts of the soul are called right, for the soul was created both with free-will and under the law of righteousness, that it might both see and do rightly.
But the members of the body being not with free-will, but under the law of sin, are called the left. Yet He does not bid us cut off the sense or appetite of the flesh; we may retain the desires of the flesh, and yet not do thereafter, but we cannot cut off the having the desires. But when we wilfully purpose and think of evil, then our right desires and right will offend us, and therefore He bids us cut them off. And these we can cut off, because our will is free.
Or otherwise; Every thing, however good in itself that offends ourselves or others, we ought to cut off from us. For example, to visit a woman with religious purposes, this good intent towards her may be called a right eye, but if often visiting her I have fallen into the net of desire, or if any looking on are offended, then the right eye, that is, something in itself good, offends me. For the “right eye” is good intention, the “right hand” is good desire.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).