Luke 11:33-36

No man, when he hath lighted a lamp, putteth it in a cellar, neither under the bushel, but on the stand, that they which enter in may see the light. The lamp of thy body is thine eye: when thine eye is single, thy whole body also is full of light; but when it is evil, thy body also is full of darkness. Look therefore whether the light that is in thee be not darkness. If therefore thy whole body be full of light, having no part dark, it shall be wholly full of light, as when the lamp with its bright shining doth give thee light.