What is so remarkable about Crowley the 'magician' is that he remains Crowley the scientist, and always applies the same probing intellectual curiosity to every field he surveys. This is ultimately the most impressive quality about his mind, and the one that might — if he had concentrated on developing it to the full — have brought him the fame that he craved. Crowley's tragedy was that he never concentrated long enough to develop anything to the full.

p. 150 - Aleister Crowley: The Nature of the Beast (1987)