Hermes Trismegistus is the title used for the syncretic figure combining the Greek god Hermes with the Egyptian god Thoth.
The name means “Hermes the Thrice-Greatest.” Hermes Trismegistus became the legendary author of a body of religious, philosophical, and esoteric writings known collectively as the Hermetica. These works were composed in Greek and Egyptian cultural settings during late antiquity, especially between the second and third centuries CE.
The figure is not simply the classical Greek Hermes under another name. He represents a later fusion of Greek and Egyptian ideas about writing, wisdom, language, astrology, and divine knowledge. The Hermetic tradition influenced Islamic, Byzantine, Renaissance, and early modern European scholarship.
The term is also connected with alchemy and the Emerald Tablet, although the surviving Hermetic texts have complex dates and authorship. Medieval and Renaissance readers often treated Hermes Trismegistus as a very ancient historical sage, a view modern scholarship does not accept literally.