Not long after Darwin's "Origin of Species" appeared I was studying with that excellent anatomist and man, Jeffries Wyman, at Harvard. He was a convert, yet so far a half-hesitating one, to Darwin's views; but I heard him make a remark that applies well to the subject I now write about. When, he said, a theory gets propounded over and over again, coming up afresh after each time orthodox criticism has buried it, and each time seeming solider and harder to abolish, you may be sure that there is truth in it. Oken and Lamarck and Chambers had been triumphantly despatched and buried, but here was Darwin making the very same heresy seem only more plausible. How often has "Science" killed off all spook philosophy, and laid ghosts and raps and "telepathy" away underground as so much popular delusion. Yet never before were these things offered us so voluminously, and never in such authentic-seeming shape or with such good credentials. The tide seems steadily to be rising, in spite of all the expedients of scientific orthodoxy. It is hard not to suspect that here may be something different from a mere chapter in human gullibility. It may be a genuine realm of natural phenomena. _Falsus in uno, falsus in omnibus_, once a cheat, always a cheat, such has been the motto of the English psychical researchers in dealing with mediums. I am disposed to think that, as a matter of policy, it has been wise. Tactically, it is far better to believe much too little than a little too much; and the exceptional credit attaching to the row of volumes of the S. P. R.'s Proceedings, is due to the fixed intention of the editors to proceed very slowly. Better a little belief tied fast, better a small investment _salted down_, than a mass of comparative insecurity.