Mora abstracts Aquinas' psychology from his many writings and demonstrates its remarkable resemblance to today's psychology. Aquinas was as learned in Plato and Aristotle as he was in Christianity. Aquinas' psychology originated from the world of intellectual thought in the twelfth century which Aquinas mastered and refined for his own uses. He developed a unified view of man combining mind and body as separate but functionally inseparable entities. He considered data gained from introspection to be valid data. His theories of intellect, memory, feeling, emotion, thought, psychophysiology, pathology of thought and feeling are all explored. Some biographical details are included, and a footnote adds a tantalizing comment that a perusal of Aquinas' life does not illuminate his intellectual concepts, but only leads to contradictions and paradoxes. One could wish for more on this. The paper is extensively footnoted; a bibliography is included in the footnotes.