“The lamp of the body is the eye. If therefore your eye is good, your whole body will be full of light. 23 But if your eye is bad, your whole body will be full of darkness. If therefore the light that is in you is darkness, how great is that darkness!” ~ Matthew 6:22-23.
The good eye looks to God as its “master” (v. 24) and fills the person with the “light” of God’s will. The bad eye looks to “treasures on earth” (v. 19) and admits only the “darkness” of greed and self-interest. The person’s whole life will be determined by the kind of “light” the “eye” lets in.