Regardie served as Crowley's secretary from 1928, fell out with him, was initiated into the Stella Matutina, a Golden Dawn successor, and then, between 1937 and 1940, published its rituals, grade papers and knowledge lectures in four volumes.
This was a straightforward breach of his oath of secrecy and was received as such; he was denounced, and the order effectively did not survive it. His defence was that the surviving temples were moribund and the material would be lost with them, and that a system this good had no business dying of secrecy. He was largely right on the facts. Every Golden Dawn revival of the last eighty years descends from what he printed, and the modern availability of a complete Western ceremonial curriculum is his doing.
The other half of his life's argument was that ceremonial magic and psychotherapy are doing the same work. He trained as a chiropractor, practised as a Reichian therapist, and insisted that nobody should attempt the higher grades without analysis first, that the rituals are instruments of psychological integration and are dangerous to an unintegrated personality. Whether that reading is a rescue of magic or a dissolution of it is still argued, but it is the frame through which most twentieth-century practitioners received the tradition.