It is evident that these exploits are still more extraordinary than the preceding ones, in certain respects. The following are the _conclusions_ of the report of Professor Porro. The phenomena are real. They cannot be explained either by fraud or by hallucination. Do they find their explanation in certain strata of the unconscious (the subliminal), in some latent faculty of the human soul, or indeed do they reveal the existence of other entities living under conditions wholly different from ours and normally inaccessible to our senses? In other words, will the _animistic_ hypothesis suffice to solve the problem and to do away with the _Spiritualistic_ hypothesis? Or, rather, do not the phenomena serve here, as in the psychology of dreams, to complicate the problem by hiding the Spiritualistic solution within them? It is to this formidable query that I am going to attempt a reply. When, eleven years ago, Alexander Aksakof stated the dilemma between Animism and Spiritism, and in a masterly work clearly proved that purely animistic manifestations were inseparable from those which direct our thoughts to a belief in the existence of independent, intelligent, and active entities, no one could have expected that the first term of the dilemma would be disputed and criticised in a thousand ways, under a thousand varying forms, by persons who would be dismayed at the second term. In fact, what are all the hypotheses which for ten years now have been invented in order to reduce mediumistic phenomena to the simple manifestation of qualities latent in the human _psyche_ (or soul), if not different forms of the animistic hypothesis, so jeered at when it appeared in the work of Aksakof? From the idea of the unconscious muscular action of the spectators (put forth half a century ago by Faraday) to the projection of protoplasmic activity or to the temporary emanation from the body of the medium imagined by Lodge; from the psychiatric doctrine of Lombroso to the psycho-physiology of Ochorowicz; from the externalization admitted by Rochas to the eso-psychism of Morselli; from the automatism of Pierre Janet to the _duplication of personality_ of Alfred Binet,--there was a perfect flood of explanations, having for their end the elimination of an exterior personality. The process was logical and in agreement with the principles of scientific philosophy, which instructs us to exhaust the possibilities of what is already known before having recourse to the unknown. But this principle, unassailable in theory, may lead to erroneous results when it is wilfully stretched too far into a given field of research. Vallati has cited, in this connection, a curious marginal note of Galileo, recently published in the third volume of the national edition of his works: