Magister Templi, numbered 8=3 and Latin for Master of the Temple, is one of the highest grades of the A A, corresponding to the grade of the same name and number in the Hermetic Order of the Golden Dawn, from which the A A adapted its structure. The order's literature treats the grades at this level as a distinct order within its overall sequence, echoing the Golden Dawn's own division between its Second Order and the higher Third Order that the older system associated with its Secret Chiefs.
The A A was founded in the early twentieth century by former Golden Dawn members, chiefly Aleister Crowley, and it published its grade requirements, this one included, in The Equinox, the order's own periodical, making Magister Templi's place in the sequence a matter of public record in the order's own primary literature rather than something reconstructed from outside description.
Crowley's own later writing on the order's structure, including his widely read essay setting out the grade system's general shape, discusses the passage into Magister Templi as a significant conceptual threshold within the A A's teaching, a framing documented in the order's published output and in the scholarly literature on Crowley's life and organizations rather than asserted here independently of that record.