THE present work deals with its subject only in a very general and, as far as the matter permits, popular way. I refer those who wish to pursue it further to the other works on Tantra sastra which are published under the name Arthur Avalon to denote that they have been written with the direct co-operation of others and in particular with the assistance of one of my friends who will not permit me to mention his name. I do not desire sole credit for what is as much their work as mine. I, in particular, refer my reader to the series of Articles on the Mantra sastra which I wrote . In this last there is given, for the first time, the rationale of Yoga through the Kundalin akti, the outlines of which are indicated in Chapter XVI of this volume.