[Concerning the invisible god] some say that he is Aapep when he riseth up with a head bearing upon it [the feather of] Maat (Truth). But others say that he is Horus when he riseth up with two heads, whereon one beareth [the feather of] Maat, and the other [the symbol of] wickedness. He bestoweth wickedness on him that worketh wickedness, and right and truth upon him that followeth righteousness and truth.
The Papyrus of Ani (The Egyptian Book of the Dead), translated by E A Wallis Budge
TO KNOW, TO DARE, TO WILL, TO KEEP SILENT, are, as we have said elsewhere, the four qabalistic words which correspond to the four letters of the tetragram and to the four hieroglyphic forms of the Sphinx. To know, is the human head; to dare, the claws of the lion; to will, the mighty flanks of the bull; to keep silent, the mystical wings of the eagle. He only maintains his position above other men who does not prostitute the secrets of his intelligence to their commentary and their laughter.
Éliphas Lévi, trans. Aleister Crowley, Liber XLVI The Key of the Mysteries