The report analyzes the concepts of the Good and the Sun in Plato’s philosophy; the influence of the concept of assimilation of the Sun to the Good on the formation of the metaphysics of light in neoplatonism, and in particular on the Julian’s philosophy, is considered. Based on the works of Julian, the three-part structure of the cosmos is reconstructed: the King of the Universe (the Good), Helios-Sun and the visible sun. Special attention will be paid to the relationship of the Helios-Sun to the visible sun and their influence on the intelligible and sensual worlds in the Julian’s hymn to King Helios. Through an analysis of the powers of the god Helios-Sun, his «middleness» will be revealed between the intelligible and sensual worlds in the Julian’s teaching.

Good, Sun, Plato, Julian, neoplatonism, metaphysics of light