This classic book explains the mental phenomena that comprise mentalism, which is a discipline which encompasses aspects of hypnosis, mental science, telepathy and other occurrences.

In twenty chapters, A. Victor Segno conducts an investigation of the major constituents of mentalist thought. Mastery of these different forms, which the author defines as manifestations of thought or etheric energy, will lead to mastery over the mind and its functions. Control of such faculties is established by being in harmony with subtle frequencies - mental vibrations - that govern the mind's ability to operate and perform such feats.

Segno describes various mental phenomena and emotional states, ranging from the experience of dreams to the honing of concentrative powers. The relation of these to successful expression of telepathic intuition or magnetic healing is described, while the subtle influence of mentalism on the development of individual personalities and destinies is explained. The physical and mental qualities of a person are molded, summed up with the phrase: "As is the mind, so is the form."