Luke 11:34-36

The eye is the lamp of your body. When your eye is clear [spiritually perceptive, focused on God], your whole body also is full of light [benefiting from God’s precepts]. But when it is bad [spiritually blind], your body also is full of darkness [devoid of God’s word]. Be careful, therefore, that the light that is in you is not darkness. So if your whole body is illuminated, with no dark part, it will be entirely bright [with light], as when the lamp gives you light with its bright rays.”