As above, so below. Hermeticism is a philosophical tradition based on writings of Hermes Trismegistus ("Thrice Great"). He wrote that a single, true theology exists which is present in all religions. Many Christian writers, including Emerson, considered Hermes to be a wise pagan prophet who foresaw the coming of Christianity. He was named Thrice Great because it was believed he knew the three parts of the wisdom of the whole universe: alchemy, astrology, & theurgy.