Matthew 6:22-23

22“The eye is the lamp of the body; so if your eye is clear [spiritually perceptive], your whole body will be full of light [benefiting from God’s precepts].

23But if your eye is bad [spiritually blind], your whole body will be full of darkness [devoid of God’s precepts]. So if the [very] light inside you [your inner self, your heart, your conscience] is darkness, how great and terrible is that darkness!