The Texts · Corpus Hermeticum X

The Key
(Corpus Hermeticum X)

Corpus Hermeticum X, The Key (Greek Kleis), is the Hermetic dialogue in which Hermes gives his son Tat a digest of earlier teaching: God as the Good that wills all things to be, the vision of that Good, the rise and fall of souls, the envelopes that carry the mind, and the human being as a mortal god. It is the tenth of the seventeen Greek treatises of the Corpus Hermeticum, in twenty-five numbered sections, and its first lines call it an abridgment (epitome) of the “General Discourses” addressed to Tat. That claim is the reason to read it: a treatise that sums up other treatises shows that someone was already reading them as a set. It also sets its limit: a summary restates, it does not decide. Where the teaching it gathers pulls two ways, The Key keeps both, and on one question, whether human souls pass into animals, it says yes in §8 and no in §19-20.

Who speaks, and what it claims to be

Hermes speaks; Tat interrupts (§4-5, 7, 9, 10, 15, 16, 20, 23). Asclepius is named only in the first sentence, as the hearer of “yesterday’s discourse”. In Mead’s version: “My yesterday’s discourse (logos) I did devote to thee, Asclepius, and so ’tis [only] right I should devote to-day’s to Tat; and this the more because ’tis the abridgment of the General Sermons (Logoi) which he has had addressed to him” (§1, Mead 1906, p. 141). Hermes cites them again in §7, and Tat at the start of CH XIII, On Rebirth.

Which discourses these were, no surviving list says. Mead admitted that “we have no means of deciding” what yesterday’s sermon was, and thought the “abridgment” wording a gloss by the editor of a collection of sermons to Asclepius and Tat, not part of the original, because the treatise reads less like a digest than like a full exposition (1906, pp. 158-160). Either way, whoever wrote the opening framed the text as a key to a set that already existed, which is why the treatise-by-treatise guide treats it as evidence that the collection was read together.

Scott prints the title as “Hermou tou Trismegistou Kleis”, the Key of Hermes Trismegistus (1924, I, p. 186), and Marsilio Ficino’s Latin, printed in 1471, heads it “Mercurii Trismegisti Clavis. Ad Tatium”. Mead, following Reitzenstein, reported that the apocryphal “Books of Moses” borrowed the title (1906, p. 158). What the key was meant to open, the treatise never says.

CH X section by section, in three editions

The table maps the twenty-five sections of the critical edition by A. D. Nock and A.-J. Festugière (vol. I, 1945), which Copenhaver (1992) follows, onto the two public-domain English versions: G.R.S. Mead’s Thrice-Greatest Hermes (1906), which uses the same section numbers, and John Everard’s Divine Pymander (1650), where the treatise is “The Fourth Book Called The Key”, cut into 94 verses of Everard’s own. The last column records ancient excerpts and editors’ notes. The headings are ours; Mead’s pages and Everard’s verses were checked in the full texts and scans.

Stobaeus references follow Wachsmuth’s edition (1884) as listed by Scott (1924, I, p. 186); Mead gives the same five excerpts in Gaisford’s older numbering. Everard’s verse 10 runs across §3 and §4, so it appears in two rows.

Key lines in public-domain translation

Four lines from Mead (1906) and one from Everard (1650), cited by section and page (Everard also by verse), spelling as printed except the long s. Square brackets are Mead’s.

“For Gnosis of the Good is holy silence and a giving holiday to every sense.” (§5, Mead 1906, p. 144)

“For it is possible, my son, that a man’s soul should be made like to God, e’en while it still is in a body, if it doth contemplate the Beauty of the Good.” (§6, p. 145)

That is Mead’s reading. The Greek text, in Scott’s edition as in Nock’s, has adynaton, “impossible”: “For it cannot be, my son, that a soul should become a god while it abides in a human body; it must be changed, and then behold the beauty of the Good, and therewith become a god” (Scott 1924, I, p. 191; Greek on p. 190).

“Now then the principles of man are thiswise vehicled: mind in the reason (logos), the reason in the soul, soul in the spirit, [and] spirit in the body.” (§13, p. 149)

“The fight of piety is to know God and to do wrong to no man.” (§19, p. 153)

“Wherefore we must be bold to say, That an Earthly man, is a mortal God; and that the heavenly God, is an immortal Man.” (§25, Everard 1650, Fourth Book, v. 93, p. 60; scan)

Mead has the same sentence as “man on earth is god subject to death, while god in heaven is man from death immune” (p. 158).

What it restates

Most themes of The Key have a home elsewhere in the Corpus, and Mead’s notes point to several. The triple name “God, Father and the Good” recalls CH II, where God is called the Good and the Father (note to §1). Vice as godlessness echoes CH XII §3, where godlessness is the soul’s great illness (note to §8). The cosmos that is beautiful but not good repeats the pessimism of CH VI, That the Good is in God Alone. The Good Daimon of §23 is the authority quoted in CH XII, and a descending chain from God through eternity to the cosmos, time and becoming runs through CH XI, the next treatise.

None of this is a fault in a summary. The trouble starts where its sources disagree, because The Key sets their claims side by side without saying which governs.

Where it does not decide

Do human souls become animals? In §7-8 souls climb a ladder from creeping things to gods, and a soul that stays vicious in a human body “speeding back again it turns into the path that leads to creeping things. This is the sentence of the vicious soul” (Mead, p. 146). In §19 no human soul may fall into the body of an animal, and in §20 Hermes calls the belief that a soul “passing from body, is changed into a beast” a grave mistake shared by “the many” and by Tat (p. 154). Mead (1906, pp. 166-167) saw “what appears to be a great difficulty” and proposed a reconciliation: §8 speaks of the ignorant soul, §19 of the soul that has the Good Mind, two classes of souls in human bodies. Walter Scott (1924, I, p. 201, note) judged instead that §19b-22a “contradicts what is said elsewhere in Libellus X, and cannot have been written by the same person.” The text does not settle which reading is right.

Who punishes the wicked? In Poimandres (CH I §23) Mind withdraws from the wicked and yields its place to an avenging daimon, who sharpens the fire and drives the soul to further crime (Mead, pp. 14-15). In §21 of The Key the avenger is mind itself: mind “becomes a daimon”, takes a fiery body to do God’s service, enters the impious soul and scourges it with its sins. Hermes then separates this “mind in service” from the Good Mind (§23). Whether this corrects CH I or simply uses other words, the treatise never says.

Why do some souls have mind and others not? §23-24 say plainly that not every soul has the Good Mind, and that mind leaves a sluggish soul tied to its body. CH IV makes mind a gift offered in a bowl to those who choose it; CH XII calls it common to all yet governing only some. The Key repeats the result and adds a prayer, “pray that thou mayst have thy mind Good [Mind]” (§22, p. 155), but gives no reason why one soul is filled and another empty.

Is the treatise one piece? Scott thought not, on two counts: §14a “was probably not written by the author of Libellus X” (I, p. 197, note), and §19b-22a came from another hand. Mead (pp. 159-160) thought the opening an editor’s gloss. Both read the text as layered; they disagree about where the layers lie.

The closing claim: a mortal god

The treatise ends on its boldest line. A human without mind should not be called human (§24); the true human is measured not with animals but with the gods, and is higher than they are, or at least their equal, because no god leaves heaven while a human climbs up and measures it “without e’en quitting earth” (§25, p. 157). Hence the human on earth is a mortal god, the god in heaven an immortal human.

The saying has a twin. In CH XII §1 Hermes quotes the Good Daimon: “Gods are immortal men, and men are mortal gods” (Mead, p. 199), which Mead traced to Heraclitus. The Key gives the same reversal a different ground. In CH XII it rests on mind being of God’s substance; here it rests on what humans do, climbing and measuring the heavens, while gods cannot come down. It is also conditional: it applies to the human who has mind, not to everyone born human. Quoted alone, it loses that condition.

The last sentence returns to the summary’s frame: all things are ordered through two, cosmos and human, but by the One (§25).

Reception

Late antiquity. Lactantius, early in the fourth century, cites Hermes naming Uranus, Saturn and Mercury among the few who had perfect learning (Divine Institutes I.11); §5 names Uranus and Cronus as forebears, but Mead argued that Lactantius had a lost treatise in mind, since X does not mention Hermes in that list (pp. 162-163). The clear witness is Johannes Stobaeus, the fifth-century anthologist, who copied five passages of The Key into the first book of his Anthology: §7-8, 12-13, 16-18, 19 and 22b-25 (Scott 1924, I, p. 186; Mead 1906, pp. 158-159). Three of them (§7-8, 12-13 and 22b-25) are headed as from Hermes’ discourses to Tat, §16-18 simply as Hermes’; in §16-18 and §22-25, Mead noted, Stobaeus makes Asclepius and Tat the speakers, which he took for a slip. The summary was already being read in pieces; for the Hermetic material that survives only in Stobaeus, see The Stobaean Fragments.

Renaissance. Ficino’s Latin version of CH I-XIV, printed at Treviso in 1471 as Mercurii Trismegisti Liber de Potestate et Sapientia Dei (Scott 1924, I, p. 31), divided the work into fourteen parts (Scott, I, p. 17, note). In the Florence copy of that printing, The Key has no printed chapter number and follows the end of the treatise on thought and sense. The Greek was first printed by Adrien Turnèbe in 1554 (Scott, I, p. 17). Francesco Patrizi rearranged the treatises in his Nova de universis philosophia (1591), and Everard’s English of 1650 follows his text and order (Scott, I, p. 43, note 3), which is why The Key is his Fourth Book, not his tenth.

Modern. Mead called it “one of the most beautiful tractates preserved to us” (p. 160) and read it through Indian and Theosophical ideas, his frame rather than the text’s. Scott (1924) rearranged it as the work of more than one author. The standard text is Nock and Festugière (1945), the standard English Copenhaver (1992, pp. 30-36). Like the rest of the collection it is a pseudepigraph, a Greek text of the Roman period put in the mouth of Hermes Trismegistus.

Translations to read

Read The Key after the treatises it gathers. As a first text it gives conclusions without arguments; as a last one it shows what an ancient reader thought the set added up to, and where it did not.

Key facts

Position	Tenth of the 17 Greek treatises of the Corpus Hermeticum, between IX (On Thought and Sense) and XI (Mind to Hermes)
Greek title	Hermou tou Trismegistou Kleis (The Key of Hermes Trismegistus); Ficino’s Latin: Clavis
Speakers	Hermes and Tat; Asclepius named only as the hearer of yesterday’s discourse
Claims to be	An abridgment (epitome) of the General Discourses (genikoi logoi) addressed to Tat (§1)
Length	25 sections (Nock-Festugière; same numbers in Mead 1906); Everard 1650: Fourth Book, verses 1-94
Ancient witness	Stobaeus, five excerpts: §7-8, 12-13, 16-18, 19, 22b-25
First in Latin	Ficino’s version, printed at Treviso in 1471 under “Mercurii Trismegisti Clavis. Ad Tatium”
Free translations	Mead 1906, vol. II, pp. 141-158; Everard 1650, pp. 40-61

Fair questions

What is Corpus Hermeticum X, The Key, about?

Hermes gives Tat a digest of earlier teaching: God as the Good that wills all things to be, the vision of the Good that transforms the soul (whether it can make a soul divine while still in the body depends on the reading of §6: Mead has “possible”, the Greek text “impossible”), the rise and fall of souls, the envelopes of mind, reason, soul, spirit and body, punishment of the impious soul by mind, and the human being as a mortal god. It calls itself an abridgment of the General Discourses addressed to Tat.

Why is it called The Key?

The text never explains the title. Its opening presents it as an abridgment of other discourses, so it works as a key to a set of teachings, and Ficino’s Latin of 1471 calls it Clavis. Mead (1906) thought the abridgment line was an editor’s gloss and reported, after Reitzenstein, that the apocryphal Books of Moses borrowed the title.

Does Corpus Hermeticum X teach that human souls become animals?

It says both. In §8 a soul that stays vicious in a human body turns back to the path of creeping things; in §19-20 no human soul may enter an animal, and the belief that it does is called a grave mistake. Mead (1906) reconciled the two by distinguishing ignorant souls from souls with the Good Mind; Scott (1924) judged §19b-22a the work of a different writer.

Where does “man on earth is a mortal god” come from?

From §25, the last section, where Everard (1650) has “an Earthly man, is a mortal God; and that the heavenly God, is an immortal Man” and Mead (1906) has “man on earth is god subject to death, while god in heaven is man from death immune”. The treatise applies it to the human who has mind, not to everyone. A similar saying of the Good Daimon opens CH XII.

Where can I read CH X for free?

In G.R.S. Mead’s Thrice-Greatest Hermes, vol. II (1906), pp. 141-158, with the same 25 section numbers as modern editions, and in John Everard’s Divine Pymander (1650) as the Fourth Book, verses 1-94, pp. 40-61; both are scanned at the Internet Archive. Scott’s Hermetica, vol. I (1924), Greek with English, is scanned there too. The scholarly standard, Copenhaver’s Hermetica (1992), is in copyright.

Sources & further reading

• G.R.S. Mead, Thrice-Greatest Hermes, vol. II (London and Benares: Theosophical Publishing Society, 1906), “Corpus Hermeticum X. (XI.) The Key of Thrice-Greatest Hermes”, pp. 141-158, commentary pp. 158-174; Poimandres §22-23 at pp. 14-15; scan at the Internet Archive. Source of the quotations marked Mead, the section-to-page map and the notes on Stobaeus, Lactantius, Theognis and Reitzenstein.
• John Everard (tr.), The Divine Pymander of Hermes Mercurius Trismegistus, in XVII Books (London: Robert White, 1650), “The Fourth Book Called The Key”, verses 1-94, pp. 40-61; Wellcome Collection copy at the Internet Archive, pages 40, 42, 53, 60 and 61 viewed 30 October 2026.
• Walter Scott, Hermetica, vol. I (Oxford: Clarendon Press, 1924), p. 17 and note (Ficino’s fourteen parts; Turnèbe 1554), p. 31 (Ficino’s 1471 edition), p. 43, note 3 (Everard follows Patrizi’s text and order), pp. 186-205 (Libellus X, Greek and English; Stobaeus excerpts listed p. 186; notes on §14a p. 197 and §19b-22a p. 201); scan at the Internet Archive.
• A. D. Nock (ed.) and A.-J. Festugière (tr.), Corpus Hermeticum, vol. I: Traités I-XII (Paris: Les Belles Lettres, 1945): Greek text of CH X and its section numbers.
• Brian P. Copenhaver, Hermetica: The Greek Corpus Hermeticum and the Latin Asclepius (Cambridge: Cambridge University Press, 1992), “Corpus Hermeticum X”, pp. 30-36, with notes; Cambridge Core.
• Marsilio Ficino (tr.), Mercurii Trismegisti Liber de Potestate et Sapientia Dei (Treviso: Gerardus de Lisa, 1471), Biblioteca Nazionale Centrale di Firenze, Magl. F.6.24: heading “Mercurii Trismegisti Clavis. Ad Tatium”; scan at the Internet Archive.
• Ioannes Stobaeus, Anthologium, ed. Curt Wachsmuth, vol. I (Berlin: Weidmann, 1884), I.47.8-9, I.48.3, I.49.48-49: the five excerpts from CH X, references as given by Scott 1924, I, p. 186.
• Lactantius, Divine Institutes I.11, tr. William Fletcher, Ante-Nicene Fathers, vol. 7 (Buffalo: Christian Literature Publishing Co., 1886); online at New Advent.
• Clement Salaman, Dorine van Oyen, William D. Wharton and Jean-Pierre Mahé (tr.), The Way of Hermes (London: Duckworth, 1999).