matthew 6:23 But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness! - Free Bible Online

      23. But if thine eye be evil--distempered, or, as we should say, If we have got a bad eye.
      thy whole body shall be full of darkness--darkened. As a vitiated eye, or an eye that looks not straight and full at its object, sees nothing as it is, so a mind and heart divided between heaven and earth is all dark.
      If therefore the light that is in thee be darkness, how great is that darkness!--As the conscience is the regulative faculty, and a man's inward purpose, scope, aim in life, determines his character--if these be not simple and heavenward, but distorted and double, what must all the other faculties and principles of our nature be which take their direction and character from these, and what must the whole man and the whole life be but a mass of darkness? In Luke (Lu 11:36) the converse of this statement very strikingly expresses what pure, beautiful, broad perceptions the clarity of the inward eye imparts: "If thy whole body therefore be full of light, having no part dark, the whole shall be full of light, as when the bright shining of a candle doth give thee light." But now for the application of this.

JFB.