In this paper, the author investigates Thomas Aquinas' succession to, transformation of and probably misunderstanding of Augustine's Imago Dei doctrines. Like Augustine, Aquinas looks for a dynamic Imago Dei in mental consciousness activities, but he changes Augustine's analogue of "memory-understanding-will" into that of "mind-understanding-will". Here he misunderstands Augustine's concept of "memoria sui/ se nosse". For Augustine, "memoria" is not a static faculty of "memory" in medieval scholastic philosophy, but a non-intentional presence of the mind to itself immediately and permanently. In modem phenomenological term, Augustine's "memoria" is the reflexive self-consciousness.