Short answer
The Corpus Hermeticum is a collection of Greek religious and philosophical treatises attributed to Hermes Trismegistus. They were probably written in Roman-era Egypt, most likely in the first to third centuries CE. The collection became central to Renaissance thinking after it was translated into Latin in the 1460s, and it is the main source for the philosophical side of Hermeticism.
What it contains
The standard collection is made up of seventeen treatises in the Greek manuscripts, though numbering and divisions vary in different editions. They are mostly dialogues in which a teacher, such as Hermes, instructs a student, such as his son Tat. Topics include the nature of God, the structure of the cosmos, the human mind and soul, and how a person may be spiritually reborn.
The Corpus is not the whole of the Hermetic literature. The Asclepius survives separately in Latin, other pieces appear in an anthology by Stobaeus, and Hermetic texts also turned up among the discoveries at Nag Hammadi. Technical Hermetica on astrology, alchemy and magic are different again. The Emerald Tablet is not part of the Corpus.
Poimandres and the creation account
The first treatise, the Poimandres, is the best known. A divine figure, Poimandres, appears to the narrator in a vision and explains the origin of the cosmos and of humanity. In the account, a divine Mind brings forth the universe, and the original Human, who shares in the divine nature, descends into the material world and becomes bound to a body. The treatise ends with a path of ascent for the person who knows himself. It has points in common with Gnostic myths, though scholars differ on how to describe the relationship.
Other themes: rebirth, mind, knowing God
Another much-discussed text is Treatise XIII, on spiritual rebirth, which describes a transformation in which the student is purified of vices and filled with divine powers. Elsewhere, the texts stress the role of nous (mind) in knowing God, and the view that the cosmos is beautiful and ordered. The authors differ from one another in tone, and some passages are more pessimistic about the body than others.
Date and origins
Scholars see the collection as the work of several authors, probably from Egypt, writing in Greek with influences from Platonism, Stoicism, Jewish thought and Egyptian religion. The relative weight of those influences is debated. The text’s claim to be ancient Egyptian wisdom is not supported by the language and ideas, but some Egyptian elements may be present.
Ficino and the Renaissance rediscovery
A manuscript of the Greek texts reached Florence in 1460. Marsilio Ficino, at the request of Cosimo de’ Medici, put aside his work on Plato to translate it into Latin, completing the first fourteen treatises in the early 1460s. His translation, titled Pimander after the first treatise, was printed in 1471 and was reprinted many times. Ficino and his readers believed the texts predated Plato and Moses, and so gave them high authority. They influenced figures such as Pico della Mirandola and Giordano Bruno, among others.
Casaubon and the redating
In 1614, the Swiss-born scholar Isaac Casaubon argued, on the basis of language and content, that the texts could not be as old as claimed and were more likely written in the early Christian centuries. This weakened the standing of the “ancient Egyptian” claim, though interest in the Hermetic tradition did not disappear. Casaubon’s dating is the foundation of the modern consensus.
Reading it today
Several English translations exist, including a widely used scholarly edition by Brian Copenhaver (1992), and the critical Greek edition by Nock and Festugière from the mid-twentieth century. Be careful not to confuse the Corpus with The Kybalion, a 1908 work shaped by New Thought that borrows the Hermetic name but is not an ancient text. For the wider context, see Western esotericism and the alchemical tradition, which both drew on Hermetic ideas.