This paper focuses on the philosophical-ethical foundations of Constantine’s definition of philosophy, as well as its anthropological and axiological aspects. The focus is placed on the relationship between definitions of philosophy postulated by Constantine the Philosopher and John of Damascus, the latter of which traces the six classical definitions systematized by Platonic commentators. Byzantine thinkers proposed a method of unifying both the theoretical and practical aspects of ancient philosophy with a Christian way of life by interpreting the classical definitions of (...) philosophy and dividing it into theoretical and practical parts, the latter including ethics. Constantine understood philosophy in the sense of the second (knowledge of things Divine and human) and the fourth (becoming like God) meanings of earlier definitions, with the addition of the Christian sense of acting in accordance with the image of God. In addition to these gnosiological and anthropological aspects, the paper also observes the axiological aspect of Constantine’s definition of philosophy, which appears to be a foundation for exploring human behaviour as in compliance with Christian laws encouraging changes in ethical principles so as to follow a new code of ethics, through which new values were presented to the Slavs. (shrink)