A Series of Reprints from the Writings of H. P. Blavatsky, this approachable introduction to Occultic knowledge is a concise and understandable starting point to your journey into the Mystic. The occult (from the Latin word occultus "clandestine, hidden, secret") is "knowledge of the hidden". In common English usage, occult refers to "knowledge of the paranormal", as opposed to "knowledge of the measurable", usually referred to as science. The term is sometimes taken to mean knowledge that "is meant only for certain people" or that "must be kept hidden", but for most practising occultists it is simply the study of a deeper spiritual reality that extends beyond pure reason and the physical sciences. The terms esoteric and arcane have very similar meanings, and in most contexts the three terms are interchangeable.