The lamp of the body is the eye. So if your eye is clear, your whole body will also be full of light.
In these words Jesus uses the “eye” as a symbolic image to show a person’s inner gaze, thinking, and spiritual perception. Just as the physical eye gives direction to the body through light, so the spiritual eye guides a person’s whole being. A “clear eye” means a pure and sincere heart, without evil thoughts. If a person’s inner gaze is directed toward God’s truth, then his whole life is filled with light—with hope, peace, and righteousness. But if the gaze is distorted, full of self-love or false interests, then the soul grows dark. These words teach that spiritual light begins with the purity of the heart, and only a pure gaze keeps a person in God’s light.