Lately I’ve had a number of people ask me to clarify what the “hermetic tradition” was and I realized that although I’ve written some blog posts dealing with the topic, I ought to make a few more clarifications. The notion of a Hermetic tradition is the work of Francis Yates and her very influential book Giordano Bruno and the Hermetic Tradition. It was this book that John Brooke used to frame Mormonism in his Refiner’s Fire. Yates’s work did much to shed light on early-modern modes of thought that had previously been under-explored but like most works, they get a little dated over time, and I will list a few of the critiques here.
One of the biggest problems was that Yates called a number of ideas “Hermetic” that were not in the Corpus Hermeticum : like astrology, alchemy, and kabbalah. Such modes of thought, Yates argued, shared a common essence with Hermetism. Though Yates always used the term “Hermetism” (the preferred term of those who study antiquity) later scholars began using the term “Hermeticism” as a broader umbrella for the practices not in the Corpus Hermeticum, but similar in essence . Thus “Hermetism” meant the ideas in the Corpus, “Hermeticism” meant the broader term. This move unfortunately created a bigger mess because the term “Hermeticism” became too vague. What was deemed Hermetic was now an intuitive judgment call, rather than a process of tying ideas back to particular sources.
Brian Copenhaver’s articles document these problems, showing that what the what the “Hermetic magi” were actually influenced by was Neoplatonism . It was the idea of Hermes Trismegistus that was particularly influential. Hermes was believed to be an ancient sage and the source of Plato’s wisdom (it was believed that Plato got his ideas from Egypt.) This meant two things: that Christian Platonic wisdom was ancient and not a new thing that began with Christ’s incarnation, and that Plato had tapped into this ancient wisdom. These ideas were particularly in vogue among Christian Platonists, or Christians who liked Plato. Their interpretation of Hermes meant that Christians could study Plato and other Platonic thinkers as sources of this ancient Christian religion . Though there’s some debate over the nature of the Corpus Hermeticum, many agree that it contains Platonic ideas (with a few twists that were Egyptian). Ultimately from the Middle Ages all the way to the nineteenth century there was not separate “hermetic tradition” apart from the larger tendency toward Christian Platonism. Those whom Yates (and Brooke) labelled “Hermetic magi” were all devotees of Plato and later Platonists .
Thus when scholars began to attack the antiquity of the Corpus Hermeticum in the 17th century, what was at stake was not the ideas contained in the Corpus Hermeticum but the idea that Christianity (as Christian Platonists understood it) was perennial, going back to Adam. The Christian Platonists believed that Adam and the antediluvians had the full, higher truth and that this truth had been spread in bits and pieces throughout all nations of the earth. Thus the Christian Platonists felt they could study the wisdom of diserve nations to understand higher Christian truths, while the anti-Platonists attacked this notion. Though Christian Platonists tended to fight for the validity of the Corpus Hermeticum throughout the 17th century, their beliefs did not rise or fall with the antiquity of those texts. What was at stake, argued Andrew Michael Ramsay was whether “God had given a complete revelation of the essential doctrines of Christianity to the earliest Patriarchs” . Whether and to what degree anything useful can be found outside the biblical canon and the Judaeo-Christian tradition also continues to be debated.
 The Corpus Hermeticum were a series of texts attributed to Hermes Trismegistus, who was believed to be a sage of great antiquity. They were translated by Marsilio Ficino in 1471. There were other writings also attributed to Hermes Trismegistus like the Asclepius. For an overview see Florian Ebeling, The Secret History of Hermes Trismegistus: Hermeticism from Ancient to Modern Times, forward by Jan Assmann trans. by David Lorton (Ithaca, N.Y.: Cornell University Press, 2007).
 This is explained in the introduction to Hermeticism and the Renaissance: Intellectual History and the Occult in Early Modern Europe, ed. by Ingrid Merkel and Allen G. Debus (Washington: Folger Shakespeare Library, 1988).
 Brian Copenhaver, “Hermes Trismegistus, Proclus, and the Question of a Philosophy of Magic in the Renaissance,” in Hermeticism and the Renaissance: Intellectual History and the Occult in Early Modern Europe, ed. by Ingrid Merkel and Allen G. Debus (Washington: Folger Shakespeare Library, 1988), 79-110; Brian P. Copenhaver, “Natural Magic, Hermeticism, and Occultism in Early Modern Science,” in Reappraisals of the Scientific Revolution (1990), 261-302.
 A good overview is Wouter J. Hanegraaff, Esotericism and the Academy: Rejected Knowledge in Western Culture (Cambridge: Cambridge University Press, 2012). Samuel Brown recently gave a good presentation on these themes a the Church History Symposium.
 A good overview of all this is Ebeling, The Secret History of Hermes Trismegistus.
 D. P. Walker. The Ancient Theology: Studies in Christian Platonism from the Fifteenth to the Eighteenth Century (Ithaca: Cornell University Press, 1972), 242.