This calm, judicious review of the results of organized psychical research cannot fail to be immensely valuable in clearing up the mists accumulated in twenty-eight years of earnest investigation into “the debatable phenomena designated by such terms as mesmeric, psychical, and spiritualistic.” The accumulations of evidence, and of argument based upon evidence, have been so enormous that few men busy with life have found time more than to dip into the wonderful subject and turn dismayed and reluctant away. Nothing has been so much needed by the Public Concerned with the Greater Things as a careful digestion of this subject to date, and we are fortunate in having so broad, so scientific, so many-sided a mind as Maeterlinck’s perform this service for us. This paper is the first of many in which ~The Century~ will take account of civilization’s accomplishments in many fields for the benefit of busy men and women.--~The Editor.~ THE THEOSOPHICAL HYPOTHESIS I have recently been studying two interesting solutions of the problem of personal survival--solutions which, although not new, have at least been lately renewed. I refer to the neotheosophical and neospiritualistic theories, which are, I think, the only ones that can be seriously discussed. The first is almost as old as man himself; but a popular movement of some magnitude in certain countries has rejuvenated the doctrine of reincarnation, or the transmigration of souls, and brought it once more into prominence. The great argument of its adherents--the chief and, when all is said, the only argument--is only a sentimental one. Their doctrine that the soul in its successive existences is purified and exalted with more or less rapidity according to its efforts and deserts is, they maintain, the only one that satisfies the irresistible instinct of justice which we bear within us. They are right, and, from this point of view, their posthumous justice is immeasurably superior to that of the barbaric heaven and the monstrous hell of the Christians, where rewards and punishments are forever meted out to virtues and vices which are for the most part puerile, unavoidable, or accidental. But this, I repeat, is only a sentimental argument, which has only an infinitesimal value in the scale of evidence.