From the sketch which has now been given of the recent treatment of the subject by popular and scientific writers, we can summarize pretty accurately their mental attitude in regard to it. They have seen very little of the phenomena themselves, and they cannot believe that others have seen much more. They have encountered people who are easily deceived by a little unexpected trickery, and they conclude that the convictions of Spiritualists generally are founded on phenomena produced, either consciously or unconsciously, in a similar way. They are so firmly convinced, on _a priori_ grounds, that the more remarkable phenomena said to happen do not really happen, that they will back their conviction against the direct testimony of any body of men, preferring to believe that they are all the victims of some mysterious delusion whenever imposture is out of the question. To influence persons in this frame of mind, it is evident that _more_ personal testimony to isolated facts is utterly useless. They have, to use the admirable expression of Dr. Carpenter, “no place in the existing fabric of their thought into which such facts can be fitted.” It is necessary, therefore, to modify the “fabric of thought” itself; and it appears to the present writer that this can best be done by a general historic sketch of the subject, and by showing, by separate lines of inquiry, how wide and varied is the evidence, and how remarkably these lines converge toward one uniform conclusion. The endeavor will be made to indicate, by typical examples of each class of evidence and without unnecessary detail, the cumulative force of the argument. HISTORICAL SKETCH.