One fact, pregnant with importance, pertains to all these systems; and that is that marvellous cures are constantly effected through their agencies. To the casual observer it would seem to be almost self-evident that, underlying all, there must be some one principle which, once understood, would show them to be identical as to cause and mode of operation. Yet we find as many conflicting theories as there are systems, and as many private opinions as there are individuals who accept the facts. Some of the hypotheses gravely put forth in books are so bizarre as to excite only the pity or the ridicule of the judicious. One notable example is found in that system, the basic theory of which is that matter has no existence, that nothing is real but mind, and that, consequently, disease and pain, suffering and death, are mere hallucinations of morbid intellects. Other theories there are, which, if not equally absurd, are probably equally remote from the truth; and each treats the persons as well as the opinions of the others with that virulent contumely which is the ever-present resort of him who would force upon his neighbor the acceptance of his own undemonstrable article of faith. Nevertheless, as before remarked, the fact remains that each of these systems effects some most wonderful results in the way of curing certain diseases. What is true of the phenomena embraced under the general head of mental therapeutics is also true of the whole range of psychological phenomena; namely, the want of a working hypothesis which shall apply to all the facts that have been observed and authenticated.