This compares healthy eyes that allow a person to see to diseased eyes that cause a person to be blind. This is a metaphor referring to spiritual health. Often Jewish people used the phrase "bad eye" to refer to greed. The meaning is that if a person is completely devoted to God and sees or considers things the way God does, then he is doing what is right. If a person is greedy for more, then he is doing what is evil. (See: [[rc://en/ta/man/jit/figs-metaphor]])