Summa Theologiae/First Part of the Second Part/Prologue

Prologue
Since, as Damascene states (De Fide Orthod. ii.), man is said to be made to God's image, in so far as the image implies an intelligent being endowed with free-will and self-movement: now that we have treated of the exemplar, i.e., God, and of those things which come forth from the power of God in accordance with His will; it remains for us to treat of His image, i.e., man, inasmuch as he too is the principle of his actions, as having free-will and control of his actions.