Aristotle, the ancient Greek philosopher of the 4th century B.C., is very well known as the founder of Logic, the propounder of Ethics and the carrier of new ideas in Metaphysics. He was a prolific writer leaving documents in almost every science and has been through the ages the guideline not only for the Greek, but also the Roman, the Byzantine, the Arabic and the Latin West civilization. In modern times he is studied extensively, but mainly from scholastic points of view [1-6]. For a psychiatrist or a psychologist of today, Aristotle is of interest because beyond being a philosopher. He proves to be a biologist and a psychologist. In his books On the Soul, On Memory, On Sleep and Dreams one can find views and theories which in many respects are very near modern psychological ideas, mainly psychoanalytic and some behaviouristic. His approach was objective and realistic and at the same time very human and down-toearth. Aristotle was a keen observer of interpersonal phenomena and studied the intrapsychic, as well as social dynamics (in his books Rhetoric and Politics). A main characteristic of the philosopher was that he held no dogmatic ideas or theories and respected all human beings, men and women, free citizens and slaves. Within this frame of thought, he accepted each person’s individuality and special characteristics, without overgeneralizations. In spite of describing the qualities attributed to an individual because of his gender, age, profession etc., he underlined the fact that each person is a distinct entity and biopsychosocial totality with particular traits, a position very close to the person-centered approach of today [7-9].