"The still more extraordinary phenomena--veridical hallucinations, warnings, detailed predictions of future events, phantoms, voices or knockings, visible or audible to numerous individuals, bell-ringing, the playing on musical instruments, stone-throwing and various movements of solid bodies, all without human contact or any discoverable physical cause, still occur among us as they have occurred in all ages. These are now being investigated, and slowly but surely are proved to be realities, although the majority of scientific men and of writers for the press still ignore the cumulative evidence and ridicule the inquirers. These phenomena being comparatively rare, are as yet known to but a limited number of persons; but the evidence for their reality is {387} also very extensive, and it is absolutely certain that during the coming century they too will be accepted as realities by all impartial students and by the majority of educated men and women." Mr. Wallace has insisted further on the utterly unscientific position of many of those who refuse to look into the evidence for these phenomena, so plainly beyond the power of the ordinary forces of nature as we know them, or of the human intelligences in the body, that are immediately around us. He deprecates, as does Galileo, the method by which this subject has been kept from receiving its due meed of attention. He points out that it is because of intellectual intolerance that this subject has been relegated to the background of scientific attention. He even contends that a great lesson is to be learned from this neglect, and one which will help men to free themselves from that burden of overconservatism which, much more than religion or theology, has impeded the progress of knowledge and the advance of science. He says: "The great lesson to be learnt from our review of this subject is, distrust of all _a priori_ judgments as to facts; for the whole history of the progress of human knowledge, and especially of that department of knowledge now known as psychical research, renders it certain that whenever the scientific men or popular teachers of any age have denied, on _a priori_ grounds of impossibility or opposition to the 'laws of nature,' the facts observed and recorded by numerous investigators of average honesty and intelligence, these deniers have always been wrong." "Future ages will, I believe, be astonished at the vast amount of energy and ignorance displayed by so many {388} of the great men of this century in opposing unpalatable truths, and in supposing that _a priori_ arguments, accusations of imposture or insanity, or personal abuse, were the proper means of determining matters of fact and of observation in any department of human knowledge."