Now who was it that said; “Let there be light?” And who was it that said to Christ concerning giving light to the world: “I have set Thee as a light to the Gentiles”—to them, that is, “who sit in darkness and in the shadow of death?” (None else, surely, than He), to whom the Spirit in the Psalm answers, in His foresight of the future, saying, “The light of Thy countenance, O Lord, hath been displayed upon us.” Now the countenance (or person) of the Lord here is Christ. Wherefore the apostle said above: “Christ, who is the image of God.” Since Christ, then, is the person of the Creator, who said, “Let there be light,” it follows that Christ and the apostles, and the gospel, and the veil, and Moses—nay, the whole of the dispensations—belong to the God who is the Creator of this world, according to the testimony of the clause (above adverted to), and certainly not to him who never said, “Let there be light.”
Tertullian
The Five Books Against Marcion, Book V
Chapter XI