"[1] According to Charles Massey, one of the founders of the Society for Psychical Research, publication of this book made the "most brutal blow" out of all ones that were ever directed against Spiritualism.

[4][note 1] At the beginning of the first chapter Hartmann explains that "the word 'Spiritism' is of French production", but the English and most part of the Germans prefer the term "Spiritualism".

[9][note 2] He believes that most people, who are aspiring for Spiritism and read Spiritist journals, have no interest in a scientific study of the phenomena of mediumship, but instead seek "the confirmation of their belief in immortality".

[11][note 3] Hartmann considers a reopening of the huge field of phenomena, that were rejected in the Age of Enlightenment, as a great merit of the modern spiritistic movement.

However, in his opinion, Spiritism threatens to become a public disaster in Germany, therefore the state should use its authority in order to interest scientists in a study of the spiritistic phenomena.

He writes that the public has the complete right to know about these things, and since it is not able to formulate its own opinion, it only remains to wait for the conclusions drawn by the official representatives of science.

[22] Hartmann believes that "from the scientific psychological standpoint" every participator of mediumistic séance must constantly think on himself that he is under the influence of a very powerful mesmerist who aims to immerse him in masked somnambulism and thus taint him with his hallucinations.

"[49][note 18] According to Hartmann, neither the sack nor the cage in which the medium can be contained will not be a hindrance to him: if he can pass through a substance in a state of sleep, "nothing prevents him from appearing as a phenomenon in front of the audience, in spite of all these precautions.

He refers to the confirmed experiments of Zöllner and the facts of "a transference" of objects into a locked room,[53] which repeatedly observed under the most stringent conditions of control.

[54] According to Hartmann, medium can't by only his will or by his purely psychological influence, cause the above-mentioned physical phenomena in inanimate objects.

Criticism by Aksakov was supported in the publications of occultists in the journal Sphinx, where "Hartmann was portrayed variously as obtuse or dishonest for his refusal to recognise his logical errors.

"[24] Aksakov has been emphasizing that Hartmann had no practical experience and did not pay enough attention to those facts that did not correspond to his convictions, and many phenomena were "completely unknown" to him.

"[71] Karl Du Prel brought such Hartmann's statement from the first chapter of his book: "Since I never attended a séance myself, I am not in a condition to form a judgment on the reality of the phenomena in question... On the other hand, I hold myself at any rate competent to offer a conditional judgment on the conclusions to be drawn from these phenomena in case of their reality, for this is peculiarly the office of the philosopher.

"[72] Then he commented on this passage as follows: "I must admit, I always believed that there is 'a golden rule for the philosopher'—to remain silent where he has no experience, so that no one could be told: 'Si tacuisses, philosophus mansisses!'