Joyce says that you put a frame around it and see it first as one thing, and that, in seeing it as one thing, you then become aware of the relationship of part to part, each part to the whole, and the whole to each of its parts. This is the essential, aesthetic factor—rhythm, the harmonious rhythm of relationships. And when a fortunate rhythm has been struck by the artist, you experience a radiance. You are held in aesthetic arrest. That is the epiphany.