The few ghost-seers whom we have at present in Germany endeavour naturally to give their mental derangement a scientific colouring, and appeal to individual professors of mathematics and natural science who happen entirely to agree with them, or are supposed to be partially inclined to do so. However, their one sheet-anchor is Zöllner, who is simply a sad proof of the fact that a professorship is no protection from madness; and they can besides, at any rate, point to opportune remarks of Helmholtz and other mathematicians on _n_ dimensions, which they, either intentionally or from mystical weakness of mind, have misunderstood. In an analytical problem the mathematician, instead of one, two, or three dimensions, may place _n_ dimensions without altering thereby the law of the problem and its legitimately resulting corollaries, but it does not occur to him to imagine, under the geometrical expression, ‘nth dimension,’ something given in space, and capable of being apprehended by the senses. When Zöllner gives the well-known example of the inversion of the india-rubber ring which, because only possible in the third dimension, necessarily appeared quite inconceivable and supernatural to a bi-dimensional being, he believes that he facilitates the comprehension of the formation of a knot in a closed ring as an operation practicable in the fourth dimension. In doing this he simply offers one more example of the known tendency of the mystic to delude himself, as he does others, with words which seem to signify something, and which a simpleton is convinced oftener than not that he understands, but which in reality express no idea, and are, therefore, empty sound, void of import.
France is about to become the promised land of believers in ghosts. Voltaire’s countrymen have already got the start of the pious Anglo-Saxons in dealings with the supernatural. I am not now thinking of the lower ranks of the people, among whom the book of dreams (_La Clé des Songes_) has never ceased to constitute the family library, together with the Calendar, and, perhaps, the ‘Paroissien’ (missal); nor of the fine ladies who at all times have ensured excellent incomes to clairvoyantes and fortune-tellers; but only of the male representatives of the educated classes. Dozens of spiritualist circles count their numbers by thousands. In numerous drawing-rooms of the best (even in the opinion of the ‘most cultured’!) society, the dead are called up. A monthly publication, _L’Initiation_, announces, in weighty tones, and with a prodigality of philosophical and scientific technicalities, the esoteric doctrine of the marvels of the unearthly. A bi-monthly publication, _Annales des Sciences Psychiques_, terms itself a ‘collection of observations and researches.’ Next to these two most important periodicals, a whole series of others exist, similar in tendency, and all having a wide circulation. Strictly technical works on hypnotism and suggestion run through edition after edition, and it has become a profitable speculation for doctors without practice, who do not attach much importance to the opinions of their colleagues, to compile so-called manuals and text-books on these subjects, which scientifically are completely worthless, but which are bought up by the public like hot rolls. Novels have, with rare exceptions, no longer any sale in France, but works on obscure phenomena of nerve function go off splendidly, so that sagacious publishers give their discouraged authors this advice: ‘Leave novels for a time, and write on magnetism.’