The present work "The Vision & the Voice" is one of those pieces that Crowley wrote as a crowning conclusion to an extensive magical operation, largely inspired by non-human intelligences. The work was first published in "The Equinox, Vol. I, No. 5" in 1911, with extensive commentary by Crowley himself, most likely from the time of his stay in Cefalu. This great work is based on the Enochian calls or keys of Dr. John Dee and Sir Edward Kelly, which Crowley studied in the Golden Dawn and somewhat later at the British Museum in London and the Ashmolean Museum in Oxford, where the original documents can be found. As early as 1900, Crowley had begun exploring the 30th Aethyr with the 19th key, with which these Aethyrs are to be summoned, in Mexico.