Luke 11:34-36

341Your eye is the lamp of your body; when your eye is 2clear, your whole body also is full of light; but when it is 3bad, your body also is full of darkness. 35So watch out that the light in you is not darkness. 36Therefore if your whole body is full of light, without any dark part, it will be wholly illuminated, as when the lamp illuminates you with its light.”