Check the listing for details. Thelema. Condition: Brand New. Listed at 28.46 USD. To truly understand the philosophy and practice of Thelema, you need to understand its charismatic founder, Aleister Crowley. This book also explores the texts and writings that form the basis of Thelema, and it provides step-by-step instructions for practicing the basic rites and rituals of this often-misunderstood tradition.