In the Byzantine writings, many aesthetic concepts are used: beauty, resemblance, similarity, imitation, harmony, symmetry, image, prototype, imagination, symbol, color, form, light, place, time, artist, creation/creativity, life-like, etc. The vocabulary can sometimes be misleading since the language of Byzantine art criticism is completely different from the modern, and thus easily misunderstood. For instance, it is difficult to see why an icon was considered as a naturalistic copy of the original, if we do not take into account the beholder’s reaction to the representation. The Byzantines’ language has a philosophical background and was derived from late antique ekphraseis, rhetorical texts that were formulated to describe an art quite different from the Byzantine. Eusebius, Procopius, Paul Silentiarios, Photios, Psellos, and many others wrote numerous ekphraseis that help us to understand the parallel function of text and art, and discourse and image in Byzantium. These descriptions try to express something of the art’s spirituality; the text shares a common end with the image described: they point to the truth that supersedes both.
The classical concept of beauty was used in the descriptions but it played no role for the iconoclastic controversy. The visible beauty, be it symmetry or appropriateness, is in earthly things and reflects the spiritual beauty of God (a theme common to the Platonic tradition). So beauty has aesthetic but more importantly ontological connotations. God is the beauty itself that surpasses and causes all created beautiful things.