The Three Initiates who authored The Kybalion chose to remain anonymous. As a result, a great deal of speculation has been made about who actually wrote the book. The most common proposal is that The Kybalion was authored by William Walker Atkinson, either alone or with others, such as Paul Foster Case and Elias Gewurz. Atkinson was known to use many pseudonyms, and to self-publish his works. Also suggestive is that among his earliest published pseudonymous and anonymous works may have been a series entitled The Arcane Teachings, which bears many superficial similarities to The Kybalion. While the latter explores seven "Hermetic Principles", The Arcane Teachings examines seven "Arcane Laws"; The Kybalion claims to be an elucidation of an ancient, unpublished Hermetic text of the same name, and The Arcane Teachings claims to reveal the wisdom of an ancient, unpublished scroll of occult aphorisms. Both books describe three "Great Planes" of reality which are further subdivided into seven lesser planes. Both also describe three of the lesser planes as "astral black keys" analogous to the black keys on a piano, and inhabited by elemental spirits. And both books describe the process of "Mental Alchemy" in great detail, and in near-complete agreement with each other. There are other similarities, and some argue that The Arcane Teachings might have been Atkinson's "first draft" of material which later became The Kybalion. Atkinson also attempted to describe the workings of the universe in terms of a set of laws in his last manuscript The Seven Cosmic Laws, written in 1931 and published posthumously in 2011.