At the heart of the book is Liber OKBISh, The Book of the Spider, a mysterious esoteric text that Grant says was received through psychic transmissions during magical rituals carried out by the New Isis Lodge in the 1950s. These oracular communications — delivered audibly and sometimes visually to various lodge members — were later assembled into the volume’s oracle sections, each accompanied by extensive commentary from Grant himself.
Grant frames the work as more than mere exposition: it reflects a long-term magical “current” that began around the late 1930s and was recognised by figures like Aleister Crowley when it first appeared in a nascent form. Through disciplined qabalistic interpretation, Grant weaves complex networks of symbolic correspondences and mystical numerology into his analysis, arguing that this reinforces the text’s legitimacy as a genuine contact with occult intelligence.
The oracles and commentary in The Ninth Arch are presented as a thesaurus of Typhonian knowledge, connecting the mystical patterns of numbers and metaphysical principles — especially for readers interested in how the physical and metaphysical might relate. Beyond this, Grant suggests that the oracles contain insights into future events affecting Earth and include warnings for individuals seeking to navigate forthcoming challenges within their personal magical frameworks.