Manly P. Hall's The Secret Teachings of All Ages (1928) is an encyclopedic outline of Masonic, Hermetic, Qabbalistic and Rosicrucian symbolical philosophy. It interprets teachings that Hall believes lie concealed in the rituals and allegories of many traditions, and the preface presents the whole as a hypothesis of living beyond materialistic thought. Hall disclaims infallibility and originality. Read it as one interpreter's working system, set out openly enough that each connection can be followed. Its ancient lineages and origin stories need evidence from outside the book.
The cryptogram chapter states the claim that ties the system together. Symbolism, Hall says, concealed sacred truths from the uninitiated and revealed them to those qualified to understand. That sentence joins two separate things: a figure that carries a meaning, and a rule that decides who receives the explanation.
In the body chapter, the analogy of macrocosm and microcosm makes the universe a Grand Man and the person a small universe. Hall then builds the analogy into the rite of admission. Where possible, he says, the temple took a body's shape, the candidate entered between its feet, and the degrees rose from a generative chamber through the heart to the brain. The correspondence thus sets the order of instruction. Hall marks its limit: images of gods were emblems, and the body is the house of the person as the temple was the house of God. He also claims that study of the body is the fountainhead of religious doctrine, which asks an analogy to prove a historical origin.
The Tarot chapter shows a correspondence without an agreed key. Hall reads the trumps as a philosophical alphabet whose cards stand for principles and combine like letters, and he records that the authorities disagree on its order. Levi places the unnumbered Fool between the 20th and 21st trumps with the letter Shin, Westcott makes it the 22nd, and Court de Gébelin and Paul Case set it first. Hall notes that the Hebrew-letter scheme rests only on both sets having 22 parts, and that the French writers' Egyptian initiation story rests on their assertion alone. In the same pages he credits Samuel Roberts with ample proof of the Roma's Egyptian origin, though the quoted passage shows only that Henry VIII's statutes described them as calling themselves Egyptians.
Hall's Eleusinian section shows the rule of admission. Relying on Gardner, Taylor and Christie, Hall describes candidates sworn to secrecy and given the title Mystes after the Lesser rites. Completing the Lesser rites was required for the Greater and did not always secure entry, and the nine days of the Greater opened with questioning on each candidate's qualifications. The highest instruction came in the hierophant's presence, and the higher teachings reached a limited number. These details concern who enters and who teaches, whatever the rites' images meant. All of it reaches the reader through the sources Hall chose.
The cipher passage describes a different kind of concealment. Secret alphabets, Hall explains, revealed that something was hidden, so writers sought systems that also concealed the presence of a message. Bacon's biliteral cipher uses two nearly identical typefaces. Each printed letter counts as a or b, and every five yield one concealed letter, so the cover text needs five times as many letters as the message. Hall works a sentence down to nine letters, then turns them on a disc cipher into ALL IS WELL. The steps can be followed one by one, and the key gives the same message to any holder, whatever that person's conduct. The trouble begins where Hall lets decoders swap a and b, read backwards or count alternate letters. Each permitted variation multiplies the candidate readings, so an intelligible phrase drawn from the Shakespeare folios cannot by itself establish Bacon's authorship.
The conclusion grounds qualification in the person's conduct. Hall argues that ancient philosophy was primarily a life and secondarily a method, and that right action, feeling and thought are prerequisites of right knowing. Joined to the cryptogram claim, this makes qualification depend on how a reader has lived, a normative and metaphysical position. He also states that the philosopher's immortality excludes the physical kind. The chapter's rankings of civilizations and rational status are separable from that argument.
The book suits a reader who wants to see how an early twentieth-century esotericist assembled correspondences across traditions and who will check historical claims elsewhere. The linked PDF is a 2005 reflow of J. B. Hare's 2001 transcription; its bibliography and index are missing. A short route: the preface, Part III of the Ancient Mysteries, The Human Body in Symbolism, the Tarot analysis, the biliteral example and the Conclusion.