Crowley explains in his essay "Gematria" that he changed the magick word to include 'H' because of qabalistic methods. He appears to say that this happened before his January 1901 meeting with Oscar Eckenstein, one of his teachers. At this meeting, Eckenstein ordered Crowley to put aside magick for the moment, and to practice meditation or concentration. In "Gematria", Crowley says he took great interest in Abrahadabra, and its qabalistic number 418, at the time someone ordered him to "abandon the study of magic and the Qabalah". In the Book of Thoth, Crowley refers to Abrahadabra as a 'cypher' of the Great Work.