An unseen world consisting of purely psychical or spiritual phenomena would accordingly be demarcated by an absolute gulf from what we call the material universe, but would not necessarily be discontinuous with the psychical phenomena which we find manifested in connection with the world of matter. The transfer of matter, or physical energy, or anything else that is quantitatively measurable, into such an unseen world, may be set down as impossible, by reason of the very definition of such a world. Any hypothesis which should assume such a transfer would involve a contradiction in terms. But the hypothesis of a survival of present psychical phenomena in such a world, after being denuded of material conditions, is not in itself absurd or self-contradictory, though it may be impossible to support it by any arguments drawn from the domain of human experience. Such is the shape which it seems to me that, in the present state of philosophy, the hypothesis of a future life must assume. We have nothing to say to gross materialistic notions of ghosts and bogies, and spirits that upset tables and whisper to ignorant vulgar women the wonderful information that you once had an aunt Susan. The unseen world imagined in our hypothesis is not connected with the present material universe by any such "invisible bonds" as would allow Bacon and Addison to come to Boston and write the silliest twaddle in the most ungrammatical English before a roomful of people who have never learned how to test what they are pleased to call the "evidence of their senses." Our hypothesis is expressly framed so as to exclude all intercourse whatever between the unseen world of spirit unconditioned by matter and the present world of spirit conditioned by matter in which all our experiences have been gathered. The hypothesis being framed in such a way, the question is, What has philosophy to say to it? Can we, by searching our experiences, find any reason for adopting such an hypothesis? Or, on the other hand, supposing we can find no such reason, would the total failure of experimental evidence justify us in rejecting it? The question is so important that I will restate it. I have imagined a world made up of psychical phenomena, freed from the material conditions under which alone we know such phenomena. Can we adduce any proof of the possibility of such a world? Or if we cannot, does our failure raise the slightest presumption that such a world is impossible?