The Kybalion (full title: The Kybalion: A Study of the Hermetic Philosophy of Ancient Egypt and Greece) is a book originally published in 1908 by "Three Initiates" (often identified as the New Thought pioneer William Walker Atkinson, 1862–1932)[1] that purports to convey the teachings of Hermes Trismegistus.

While it shares with ancient and medieval Hermetic texts a number of traits such as philosophical mentalism, the concept of 'as above, so below', and the idea that everything consists of gendered polar opposites, as a whole it is more indebted to the ideas of modern occultist authors, especially those of the New Thought movement to which Atkinson belonged.

"[11]According to occult writer Mitch Horowitz, the philosophical mentalism (the primacy of mind as the active cause of things) described by the Kybalion's first principle was inspired by broadly similar notions in the ancient Greek Hermetica.

[12] Nicholas E. Chapel notes that while several aspects such as the philosophical mentalism, the concept of "as above, so below" as derived from the Emerald Tablet, and the idea that everything exists as pairs of gendered polar opposites, do have a background in ancient and medieval Hermetic texts, other aspects such as the principle of vibration (which originates in the philosophy of David Hartley, 1705–1757) are not related to Hermeticism.

Chapel concludes that as a whole, the Kybalion is too bound up with early 20th-century ideas emanating from the New Thought movement to be representative of the broader historical tradition of Hermetic philosophy.