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View of one of the four Seraphim that are located in the four pendentives of the church of Hagia Sophia. A seraph is a heavenly being that is described in Isaiah 6:2–3 “Above him were seraphs, each with six wings: With two wings they covered their faces, with two they covered their feet, and with two they were flying. And they were calling to one another: “Holy, holy, holy is the LORD Almighty; the whole earth is full of his glory.””
Note the representation of two wings extended—as if flying, two wings covering the feet, and two wings covering its face. In Orthodox worship there is an emphasis on how the beings in the heavenly realm (seraphim, cherubim, departed saints, etc.) join with the saints in the earthly realm in praise of God. The earthly saints are gathered in the nave of the church, while the heavenly realm is represented in the dome.
For a brief description of the Hagia Sophia Click Here .