"_The more I think of it, the more I find this conclusion impressed upon me, that the greatest thing a human soul ever does in this world is to SEE something and tell what it saw in a plain way. Hundreds of people can talk for one who can think, but thousands can think for one who can see. To SEE clearly is poetry, prophecy, and religion all in one._"--JOHN RUSKIN. WORKING HYPOTHESIS That under certain known and reasonable conditions of temperature, light, etc., entities, existing in a sphere outside our own, have been demonstrated again and again to manifest themselves on earth in temporary bodies materialized from an, at present, undiscovered source, through the agency of certain persons of both sexes, termed "sensitives," and can be so demonstrated to any person who will provide the conditions proved to be necessary for such a demonstration. CONDITIONS Looking back to the seven years of my life which I devoted to a careful and critical investigation of the claim made, not only by both Occidental and Oriental mystics but by well-known men of science like Sir William Crookes, Professor Alfred Russel Wallace, and others--that it was possible under certain clearly defined conditions to produce, apparently out of nothing, fully formed bodies, inhabited by (presumably) human entities from another sphere--the wonder of it still enthralls me; the apparent impossibility of so great an upheaval of such laws of Nature as we are at present acquainted with being proved clearly to be possible, will remain to the end as "the wonder of wonders" in a by no means uneventful life. For, as compared with this, that greatest of Nature's mysteries--the procreation of a human infant by either the normal or mechanical impregnation of an ovum, its months of foetal growth and development in the uterus, and its birth into the world in a helpless and enfeebled condition, amazing as they are to all physiological students--sinks into comparative insignificance when compared with the nearly instantaneous production of a fully developed human body, with all its organs functioning properly; a body inhabited temporarily by a thinking, reasoning entity, who can see, hear, taste, smell and touch: a body which can be handled, weighed, measured, and photographed. When these claims were first brought to my notice I realized at once that I was face to face with a problem which would require the very closest investigation; and I then and there decided to give up work of all kinds and to devote years, if necessary, to a critical examination of these claims, to investigate the matter calmly and dispassionately, and, in Sir John Herschel's memorable words, "to stand or fall by the result of a direct appeal to facts in the first instance, _and of strict logical deduction from them afterwards_."