The supposed communication of one mind with another at a distance, without any means known to physical or psychological science, is a generally accepted definition of telepathy. Thus when persons sensorially isolated from each other experience congruence and coincidence of thoughts, emotions or actions they are considered as being in telepathic communication. Clairvoyance surmises the apprehension of particular objects and stimuli also without the employment of any of the agencies of the five senses. Although telepathy and clairvoyance have been thus recognized as distinct conjectures, either or both comprise features of Extra Sensory Perception (ESP). Both are conceived of as transcending the anatomical structures and physiological functionings that comprise the five senses. They therefore constitute a mysterious, additional sense which as yet cannot be ascribed to material bases or causes. However, the operations, if not the exact natures, of these recondite abilities have been, it is claimed, experimentally and precisely ascertained.