The readers are presented with “Nicomachean Ethics” - one of the three ethical works of the ancient Greek philosopher Aristotle (384 BC - 322 BC) - a student of Plato and mentor of Alexander the Great. Distinguishing between natural scientific and moral psychology, Aristotle devoted this work specifically to moral psychology, focusing his attention on the psychological basis of a person’s moral character (books 1 and 6 of the Nicomachean Ethics). In subsequent books, the author, discussing the negative sides of human character, friendship and the contemplative life, strives for a philosophical definition of the concept of “happiness.”