was not normal.  The opinion of Wundt, as of a man whose profession would not permit him to speak hastily upon this topic, I would regard as of special value; but if we rule that out upon the ground that Wundt was not impressed by the investigation, and might naturally be inclined to underrate Zoellner, who was, we have left the opinions of Fechner and Scheibner, both Zoellner’s colleagues at Leipsic, both particular friends of Zoellner, and both inclined to agree with him as to the reality of the facts he describes.  Both of them regarded Zoellner at the time as of more or less unsound mind.  His disease, as described by them, seems to have been chiefly emotional, showing itself in a passionate dislike of contradiction, and a tendency to overlook any evidence contrary to a cherished theory.

To the general change in his nature due to his disease Professor Scheibner testifies; and Professor Fechner’s belief as to his mental condition is specially worthy of note from the fact that, although recognizing it to be abnormal, he still holds his powers of observation to be sound, and upon this ground is inclined to assent to the facts described.  If anyone could be tempted to make Zoellner as sane as possible, it would be one in the position of Professor Fechner.  Professor Weber’s testimony I will examine later.  Upon the question whether the peculiar form of Zoellner’s disease would be likely to affect his powers of observation, the following points may throw some light.

(2.) It is evident, both from what Zoellner has himself printed and from what Professor Scheibner has said, that Zoellner’s interest in the investigation centered in his attempt to prove experimentally what he already held to be speculatively true as to a fourth dimension of space.  In a paper published in the Quarterly Journal of Science, for April, 1878, he says: 

“At the end of my first treatise, already finished in manuscript in the course of August, 1877, I called attention to the circumstance that a certain number of physical phenomena, which, by ’synthetical conclusions a priori’ might be explained through the generalized conception of space and the platonic hypothesis of projection, coincided with so-called Spiritualistic phenomena.  Cautiously, however, I said:—­’To those of my readers who are inclined to see in Spiritualistic phenomena an empirical confirmation of those phenomena above deduced in regard to their theoretical possibility, I beg to observe that from the point of view of idealism there must first be given a precise definition and criticism of objective reality’” etc.  Now this reference to Spiritualistic phenomena was made before Zoellner had seen anything of the kind, and his attitude was evidently a receptive one.  Moreover, we have Professor Scheibner’s testimony to the fact that during the whole investigation his attention was entirely directed towards the subject of the fourth dimension, and an experimental demonstration