This is one of Atkinsons' three works on the subject of Yoga, specifically in this edition, Gnani (or Jnani) yoga, one of the main parts of the system.
The book is well written and very interesting, but it ought to be noted that unlike the prior title on Raja yoga, this work is much more philosophical than how-to, and is clearly and purely a Western look at yoga, as opposed to one...
This work is notable for its extensive treatment of the history of faith healing, mesmerism, hypnosis, and similar topics. The overarching topic is, in the latter half, about suggestion, but leads up to it by presenting material about how cells communicate with one another, and some various philosophy. Some of its material is badly dated but other content has held up over time...