As adopted son of Thermuthis (daughter of Sesostris-Rameses, priestess of Hathor and Neith), and as Regent Potential, he had access to the most secret teachings of the temple. At that time Egyptian worship was directed to the celestial Amon 'who sheds Light on hidden things.' These 'hidden things' comprised much of our 'visible' science -- architecture, geology, biology, astronomy, psychology and medicine -- plus those occult disciplines which deal with the 'invisible' laws and forces which govern our universe.
Here possibly is where the idea of horns originates. For in the Mystery language horns are the sign of the successful neophyte, of one who has passed the dread tests of initiation and quite literally touched divinity.
But later, after the State had taken over the supervision of the Mystery schools, the spirit of their teachings became obscured so that the horn came to symbolize the conqueror of worlds rather than the conqueror of self. Thus Jamshid, builder of Persepolis, was called 'the two-horned.' And Alexander the Great, initiated by the oracle at the desert oasis Temple of Amon in 332 B.C., accepted as an inestimable honor the horned AKKADIAN CYLINDER SEAL headdress. He wore it with pride as did the 'initiated' of the Egyptians, Greeks, and Romans. To them, as to the Vikings, horns meant power of the spirit. So with the Celts who inscribed the likeness of their teacher, Cernunnos, 'the horned,' on a silver plaque, sitting in a Krishna pose and holding this emblem in the form of a ram-headed serpent in his hand.
So with horns, Michelangelo acclaimed Moses a man of power and station far greater than lawgiver of a local tribe. With horns he saluted him not only as one who had stood in the presence of God, and had realized, had become at-one with, his own divinity, but nobler far, as a man fulfilled who had returned -- for some do not. Only the few come back, down the mountain, in order to teach and lead mankind.
The horns themselves are an interesting symbol, for sheep, especially those native to the wild mountain areas of Asia and North America, are surefooted climbers who courageously ascend the most stark perpendiculars; while their domesticated cousins are so gentle that primitive religions readily incorporated them into their art forms. Apollo, Mercury, and later Jesus were all pictured as Good Shepherds with lambs either carried on their shoulders or couching at their feet.
Moses was without doubt accustomed to seeing ram-headed figures painted on the walls of the royal tombs, where they represented the Sun-God, Amon (later Amon-Ra). During the 6th and 7th centuries B.C. this deity was depicted in the likeness of a man, standing or seated as the Moses of Michelangelo, and frequently wearing the headmask of a ram. Those who interpret Egyptian belief explain that he symbolizes first, the Pleroma, the Fullness of things, and then, that creative force in nature which initiates and maintains intelligent life in this and in the lower worlds. For Amon-Ra was also presented enthroned on a solar boat journeying through the twelve hours of the night to illumine the Underworld.
The Greeks used Pan to express this idea. Horned, hoofed, tailed and sometimes bearded, he with his band of exuberant fawns and satyrs perennially disrupt the status quo.