It may be worth while to consider for a few moments the mode in which new knowledge enters the mind. By new knowledge is meant not extension of existing knowledge, but facts of a new order, such, for instance, as the rising of a heavy dining table into the air without any recognised physical cause being apparent. The difficulty of admitting new facts of this kind to the mind is not confined to any one class of people. Indeed the difficulty appears to be greater in the case of highly educated people than among the comparatively uninformed. Sir Oliver Lodge has recently said: "What does a 'proof' mean? A proof means destroying the isolation of an observed fact or experience by linking it on with all pre-existent knowledge; it means the bringing it into its place in the system of knowledge; and it affords the same sort of gratification as finding the right place for a queer-shaped piece in a puzzle-map. Do not let these puzzle-maps go out of fashion; they afford a most useful psychological illustration; the foundation of every organised system of truth is bound up with them.... It is because a number of phenomena, such as clairvoyance, physical movement without contact, and other apparent abnormalities and unusualnesses, cannot at present be linked on with the rest of knowledge in a coherent stream--it is for that reason that they are not, as yet, generally recognised as true; they stand at present outside the realms of science; they will be presently incorporated into that kingdom, and annexed by the progress of discovery."[68] Mr. F. C. S. Schiller, in an article in the _Proceedings_ of the Society for Psychical Research, expresses a similar thought in a different manner. He says:-- "A mind unwilling to believe, or even undesirous to be instructed, our weightiest evidence must ever fail to impress. It will insist on taking that evidence in bits, and rejecting it item by item. The man therefore who announces his intention of waiting until a single absolutely conclusive bit of evidence turns up, is really a man _not_ open to conviction, and if he is a logician, _he knows it_. For modern logic has made it plain that single facts can never be 'proved,' except by their coherence in a system. But as all the facts come singly, any one who dismisses them one by one, is destroying the conditions under which the conviction of new truth could arise in his mind."[69] Mr. Myers, in summing up the evidence in the case of Mr. Stainton Moses, dwells on the importance of simple repetition. This, though practically effective, is scarcely a scientific consideration. A fact is none the less a fact on account of the rarity of its occurrence, any more than the existence of a rare animal or plant is rendered questionable by the fewness of the number of specimens which have been found.