On Orthodox icons Christ is represented with an halo on which we can see the inscription – Ὁ ὬΝ – He Who Is. Which theological foundations support this kind of iconographical depiction? How and why did the words by which God revealed Himself to the Old Testament Israel as He Who Is – Εγώ εἰμι ὁ ὤν (Exodus 3, 14 LXX) appeared on Christ’s halo? How are this iconographical solution, Old Testament epiphanies and Christ connected? In the present article, we will try to show the assumptions which served as the basis of this understanding, more precisely the interpretation which would led to this kind of iconographical solution, i. e. which would justify this praxis inherent to Orthodox iconography.