Thirdly, the vital power of man, as you say, can manifest its activity only by means of its material organs. This is true; for, so long as the soul is in the body, it must work together with it, according to the axiom, “Every agent acts according as it is in act.” But does the work of the vital power in the material organs warrant your conclusion that the soul needs to be supported by a material substratum? Quite the contrary. For, what needs a material substratum is an accident, and no accident is active; and therefore the vital power, whose activity is manifested in the material organs, is no accident, and therefore needs no material substratum, and, while existing in the material organs, exists no less in itself. Had you considered that the soul, which manifests its activity by means of its material organs, exercises the same activity within itself also, you would have easily discovered that the soul has a being independent of its material organs, and that these organs are the organs of sensibility, not of intelligence. But I am not going to make a dissertation on the soul, as my object is only to show the inconclusiveness of your reasoning. Your chapter on “Brain and Soul,” with its twenty‐eight pages of medical and physiological erudition, offers no proof of your assumption beyond the three sophisms I have refuted. All the rest consists of facts which have not the least bearing on the question. “The whole science of man,” as you say, “is a continuous proof in favor of the connection of brain and mind.” This is what your facts demonstrate; but your object was to show that “the soul is a product of the development of the brain”; and this your facts do not demonstrate, as is evident from your need of resorting to fallacies to make them lie to truth. It is on the strength of such fallacies that you make bold to despise your opponents, forgetting all your shortcomings, and committing a new blunder in the very act of assailing the spiritualistic philosophers. According to you, “the whole science of man is a continuous proof in favor of the connection of brain and mind; and all the verbiage of philosophical psychologists in regard to the separate existence of the soul and its independence of its material organ is without the least value in opposition to the power of facts.” You should be ashamed, doctor, of this style of reasoning. _Büchner._ Why, if you please?