The lamp of the body is the eye. Therefore, when your eye is good, your whole body also is full of light. 

The natural man does not receive the things of the Spirit of God, for they are foolishness to him; nor can he know them, because they are spiritually discerned. Open my eyes, that I may see wondrous things from Your law.I am the light of the world. He who follows Me shall not walk in darkness, but have the light of life. § We all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image … just as by the Spirit of the Lord. It is the God who commanded light to shine out of darkness, who has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ.The God of our Lord Jesus Christ, the Father of glory … give to you the spirit of wisdom and revelation in the knowledge of Him … that you may know what is the hope of His calling, what are the riches of the glory of His inheritance in the saints.