Aleister Crowley encountered yogic practices relatively early in his occult career and included its study and practice in A.’.A.’. training, wrote his own “Eight Lecture on Yoga” and discusses it in Liber E and Liber RV and other diverse publications. Here’re some interesting observations by a latter day yogic practitioner, Ken McLeod – a student of Kalu Rinpoche – focused on Vajrayana belief and practice. He discusses his views on this tradition which he feels is based on renunciation, retreat from society and in the search for “powers and transcendent experiences through the practice of sorcery and energy transformation. “
http://reflectionsoninfinitespace.blogspot.com/2014/11/an-overview-of-vajrayana.html