"Beginning with discovering the dual nature of the voice, the writer of this book opened up the way to the comprehension of the mystery of man's dual nature in _all_ its relations. He made the discovery that the œsophagus is of equal importance with the trachea in carrying on the process of respiration and in exercising the faculty of vocal expression; that for these purposes œsophagus and trachea are to an equal degree directly amenable to the influence of the atmospheric air; that the dual nature of organic beings in general, and of man in particular, is represented by the hemispheres of the thorax and the abdomen; that the former in its entirety represents spiritual and the latter in its entirety material issues; that the trachea and its branches on the one hand, and the alimentary canal on the other, respectively represent these issues more directly; that the fusing and blending of these issues has for its result the phenomenon called life; that the severance of these issues has for its result the phenomenon called death; that there are thus positive limits, place, and surroundings assigned to material and immaterial issues within the sphere of our bodily existence, and that combined they pervade our entire system; that all phenomena of life, especially all phenomena of a spiritual nature, and among these more ostensibly those of vocal utterance, owe their origin to these issues momentarily joining hands; that in so doing there is a transitory fusion, which for an endless number of purposes is brought about in an endless number of ways. "He discovered further that the larynx, previously supposed to be the _only_ instrument for the production of sounds, has its counterpart in the 'replica' (the 'larynx' of the œsophagus), located beneath the tongue and represented by the frænum linguæ and surrounding cartilaginous tissues; that no vocal sound can be produced except by the coöperation of the larynx with the replica. He discovered the circulation of, and the origin of vocal sounds, and many other important issues. "Through his discoveries, if properly recognized, _all_ the sciences dealing with life would have been placed upon a new and far more reasonable and comprehensible basis than they had rested upon before. "These discoveries would have tended to undermine the basis of every materialistic school of philosophy, and to place those with spiritual and ideal propensities upon higher and firmer ground. Had they been properly appreciated and further expanded by others it would have eventually become possible to develop _all_ our faculties to the full extent of their ability, and to correct faults, errors, and defects caused by wrong education or heredity, through the application of laws at the very root of our existence; laws which were then, and in fact to a great extent are to this day unknown.