The next pioneer--fortunately still amongst us--whom I must mention even in this summary notice, is the celebrated physicist and chemist, Sir W. Crookes. Just as Swedenborg was the first leading man of science who distinctly conceived of the spiritual world as a world of law, so was Sir W. Crookes the first leading man of science who seriously endeavoured to test the alleged mutual influence and interpenetration of the spiritual world and our own by experiments of scientific precision.[3] Beyond the establishment of certain supernormal facts Crookes declined to go. But a large group of persons have founded upon these and similar facts a scheme of belief known as Modern Spiritualism, or Spiritism. Later chapters in this book will show how much I owe to certain observations made by members of this group--how often my own conclusions concur with conclusions at which they have previously arrived. And yet this work of mine is in large measure a critical attack upon the main Spiritist position, as held, say, by Mr. A. R. Wallace, its most eminent living supporter,--the belief, namely, that all or almost all supernormal phenomena are due to the action of spirits of the dead. By far the larger proportion, as I hold, are due to the action of the still embodied spirit of the agent or percipient himself. Apart from speculative differences, moreover, I altogether dissent from the conversion into a sectarian creed of what I hold should be a branch of scientific inquiry, growing naturally out of our existing knowledge. It is, I believe, largely to this temper of uncritical acceptance, degenerating often into blind credulity, that we must refer the lack of progress in Spiritualistic literature, and the encouragement which has often been bestowed upon manifest fraud,--so often, indeed, as to create among scientific men a strong indisposition to the study of phenomena recorded or advocated in a tone so alien from Science.