In the resolution proclaiming 2015 the International Year of Light and Light-based Technologies, the General Assembly of the United Nations drew atten- tion to the importance of light in the lives of the citizens of the world. This is of major importance, not only because light plays a crucial role in fields as diverse as arts, culture or technology, but also because ‘light’ is a major concept within the history of philosophy. Since the first Presocratic philosophers, light had an important (...) role in their philoso- phical systems and was one of the most resourceful concepts explaining realities and conveying their properties. Since these world-visions ‘light’ was much more than a physical reality or a symbol; it was a powerful metaphor, sometimes used against some ideas of ignorance, obscurantism or even evil. The relevance of Neoplatonist thinkers is proved by the extensive translations and commentaries undertaken during Middle Ages, which influenced art, physics, optics,and aesthetics. This paper will pay particular attention to the discussion of the concept of ‘light (phos)’ in Plotinus’ Enneads, and then we will discuss its metamorphosis in the thought of philosophers such as Proclus, Damascius and Pseudo-Dionysius the Areopagite. (shrink)