As individuals bring their raw potentials into existence, the human race evolves. Trance states are the means through which these transformations take place. Trances are concentrated states of engagement with the world. They occur frequently in the ordinary course of living. Hypnosis is merely one variety of trance, but its study has led to a profound understanding of trance states in general. The idea that trance constitutes the technology for human advance has developed for Dr. Crabtree over a period of some thirty years. Memoir of a Trance Therapist is the story of that development, along with an explanation of the central elements of Dr. Crabtree's vision.