Harmakhis, "Horus of the Horizon," personified the rising sun and was associated with Khepri as symbolizing resurrection and eternal life. Though sometimes represented as a falcon-headed man wearing a variety of crowns or sometimes as a falcon-headed lion or a ram-headed lion, his most famous representation was as the Sphinx of Giza, a vast man-headed wearing the royal headdress and the uraeus. This was sculptured out of living rock near the tomb of Khepren, a pharaoh of the Fourth Dynasty, the face being in his image; sphinxes were usually identified with the pharaoh in his immortal aspect.
Harmakhis was considered to be not only the sun god as Horus, but also the repository of the deepest wisdom. Thuthmosis III in the Eighteenth Dynasty told how, when he was a young prince out hunting, he chanced to fall asleep at noon in the shadow between the great paws of Harmakhis of Giza. In his dream he heard a voice saying, "Behold me, my son, Thuthmosis, I am thy father Harmakhis-Atum-Khepri. Thou shalt assume the white crown and the red crown upon the Throne of Geb." The god continued explaining that he would obtain the throne for Thuthmosis provided that he in return would remove the sand that had over the centuries half buried the sphinx. Thuthmosis rendered this service to Harmakhis, and thus in due time became pharaoh; that is, under the protection of Re-Harmakhis rather than Amom-Re. So began the movement against Amom-Re that would culminate Atenism. A.G.H.
Ions, Veronuca, Egyptian Mythology, Feltham, Middlesex, Hamlyn Publishing Group, Ltd., 1968. pp. 70-71