“The lamp of the body is the eye.”

And while the crowds were thickly gathered together, He began to say, “This is an evil generation. It seeks a  sign, and no sign will be given to it except the sign of Jonah  the prophet. For as  Jonah became a sign to the Ninevites, so also the Son of Man will be to this generation. The queen of the South will rise up in the judgment with the men of this generation and condemn them, for she came from the ends of the earth to hear the wisdom of Solomon; and indeed a  greater than Solomon is here. The men of Nineveh will rise up in the judgment with this generation and condemn it, for  they repented at the preaching of Jonah; and indeed a greater than Jonah is here. “No one, when he has lit a lamp, puts it in a secret place or under a  basket, but on a lampstand, that those who come in may see the light. The lamp of the body is the eye. Therefore, when your eye is  good, your whole body also is full of light. But when your eye is  bad, your body also is full of darkness. Therefore take heed that the light which is in you is not darkness. If then your whole body is full of light, having no part dark, the whole body will be full of light, as when the bright shining of a lamp gives you light.”
Luke 11:29-36 -NKJV