RobH_en_tn/mat/06/23.md

But if your eye ... how great is that darkness

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/translate/figs-metaphor)

if your eye is bad

This does not refer to magic. Jewish people often used this as a metaphor for someone who is greedy. (See: rc://en/ta/man/translate/figs-metaphor)

if the light that is in you is actually darkness, how great is that darkness!

"if that which is supposed to cause light in your body causes darkness, then your body is in complete darkness"