What is Hermes Trismegistus?
Hermes Trismegistus is a legendary literary figure from late-antique Alexandria, not a historical person. The name blends the Egyptian god Thoth with the Greek Hermes to create the supposed author of the Corpus Hermeticum and the founding ancestor of the Hermetic tradition.
Hermes Trismegistus, Thoth, and the Greek Hermes
The modern reception that treats Hermes Trismegistus as a historical person, as in the phrase the ancient Egyptian sage Hermes Trismegistus taught that..., is reproducing the Renaissance error Isaac Casaubon dismantled in 1614. The Corpus Hermeticum was composed in the second and third centuries CE by anonymous Greek-writing authors in Roman Egypt. The figure is the literary attribution under which the texts circulate, not the person who produced them. He is also not the Egyptian Thoth. The identification of the two gods was an act of Hellenistic syncretism that the Egyptian temple priesthood neither initiated nor universally accepted. The corpus produced under the syncretic name is a Greek philosophical literature with Egyptian decorative elements, not a faithful transmission of older Egyptian religious thought. The figure is not the classical Greek Hermes either. The Trismegistus compound is a late-antique elaboration of the messenger god into a contemplative authority the earlier Greek tradition would not have recognised.
Origins of the figure
Hermes Trismegistus (Greek Ἑρμῆς ὁ Τρισμέγιστος, thrice-greatest Hermes) is the syncretic literary figure assembled in late antiquity from two prior gods. The Egyptian Thoth was the scribe of the gods, inventor of writing, patron of scribes and weigher of hearts at the post-mortem judgement. He had been the local deity of Khemenu (Hermopolis Magna) in middle Egypt since at least the third millennium BCE. The Greek Hermes was the messenger of the Olympians, psychopomp and patron of travellers, traders and translators. After Alexander's conquest of Egypt in 332 BCE, Hellenistic settlers applied the interpretatio graeca and identified Thoth with Hermes. By the first century CE, the compound figure this identification produced had become the named author of a substantial esoteric literature: the Corpus Hermeticum, the Asclepius, the Stobaean fragments, and a much larger alchemical and astrological corpus. The thrice-greatest epithet first appears in the second century CE. Some classical sources read it as greatest priest, greatest philosopher, greatest king; others as a Greek translation of an Egyptian compound Thoth the great, the great, the great attested in Demotic temple inscriptions from the Hellenistic period.
The Corpus Hermeticum and the technical literature
The philosophical Hermetica are the seventeen tractates of the Corpus Hermeticum surviving in Greek and the longer Asclepius surviving in Latin. They were composed between roughly the first and third centuries CE by anonymous Greek-speaking authors in Alexandria, who attributed their work to Hermes Trismegistus on the same generic-author convention the period applied to the Sibylline Oracles and the Orphic poems. The first tractate, the Poimandres, sets the tone the corpus carries throughout. A divine intelligence, also called Poimandres meaning shepherd of men, appears to the seer Hermes and reveals the structure of the cosmos, the descent of the soul into matter, and the contemplative ascent by which the soul is reunited with its divine source. The metaphysics is mentalist: the cosmos is the product of a divine Nous, the human is a microcosm in correspondence with the macrocosm, and the practitioner's task is the disciplined ascent through the planetary spheres to the unmanifest Good beyond them. The technical Hermetica are the operational counterpart: alchemical, astrological, magical and iatromathematical literature that translates this metaphysics into procedures. The same figure is named as the author of both registers.
Renaissance reinvention and Casaubon's dating
The Greek Corpus was lost to the Latin West after the Alexandrian schools closed in the fifth and sixth centuries. The Arabic-speaking world preserved the technical Hermetica and built on them through Jābir ibn Ḥayyān and the medieval Arabic alchemical tradition, but the philosophical tractates did not re-enter the Latin orbit until 1453, when the fall of Constantinople carried Greek manuscripts west. Marsilio Ficino, working for Cosimo de' Medici in Florence, was instructed in 1463 to set aside his Plato translation and turn first to a newly arrived Greek codex of the Corpus Hermeticum. Cosimo believed the Hermetic texts were older than Plato and contained the prisca theologia, the ancient theology from which Greek philosophy itself derived. Ficino completed the Latin translation within a few months. His Pimander became one of the foundational documents of the Italian Renaissance. The figures who built on it, among them Giovanni Pico della Mirandola, Giordano Bruno, John Dee, Robert Fludd, Athanasius Kircher and Isaac Newton, read the corpus as the recovered wisdom of an Egyptian sage who had taught Moses, anticipated Plato and prefigured Christ. The dating did not survive scrutiny. The French Protestant scholar Isaac Casaubon, in his 1614 De rebus sacris et ecclesiasticis exercitationes XVI, demonstrated on linguistic and doctrinal grounds that the Corpus Hermeticum was a composition of the early Christian centuries, not of pre-Mosaic antiquity. His dating has not been seriously disputed since. By the late seventeenth century, the Hermetic tradition had retreated from mainstream European philosophy into the Rosicrucian, Masonic and esoteric currents that have carried it from the eighteenth century to the present.
The figure in the lexicon
Hermes Trismegistus is not himself a row in the index. No contemporary spiritual-media item in the corpus has him as its primary subject, and the entry exists for cross-link weight. He is the named source the Hermeticism entry begins from, the supposed author the Kybalion presents itself as a digest of, and the figure under whose authority the sacred geometry tradition's as above, so below formula descends. He is also the structural ancestor of the New Thought, Theosophical and Law of Attraction currents that the modern Anglophone esoteric publishing landscape continues to produce. The connections run wide: the late-antique Neoplatonism of Plotinus and the Corpus Hermeticum are products of the same Alexandrian milieu. Kabbalistic reception in the medieval and Renaissance period drew on Hermetic correspondences in articulating the sefirot. The Gnostic cosmogonies preserved at Nag Hammadi share more with the Poimandres than with anything in canonical Christian theology. Hermes Trismegistus is the most efficient single carrier the Western esoteric tradition has found for the mentalist and correspondence doctrines the Hermetic family of traditions has carried for two millennia.