[63] We shall do well to note that Nicolai practically considers himself exempt from the need for these material demonstrations. As far as he is concerned, it would suffice him, as it sufficed Aristotle, to observe the play of forces among men. This simple observation would convince him that humanity must be regarded as an organism. "But moderns, although they will generally deny it, are for the most part infected with the belief that all solid fact must be material.... Even though it be not absolutely necessary to demonstrate that there exists between human beings a bridge of real substance (eine Brücke realer Substanz), even though the dynamic ties suffice us, it is desirable to satisfy the materialistic demands of our day, and to show that there does actually exist between the men of all ages and all lands an effective interconnection, which is uniform, persistent, nay eternal" [pp. 392-393, English edition]. [64] According to this theory, which was initiated by Gustav Jaeger in 1878, there occurs an eternal transmission of an inheritable germ plasm, this being temporarily housed within the perishable soma of the individual living being. The hypothesis of the undying plasma has given rise to lively discussions which are still in progress. [65] Ueber Ursprung und Bedeutung der Amphimixis, "Biolog. Zentralblatt," xxvi, No. 22, 1906. [66] This seems to me the weak point in the theory. How can we reconcile the mutation and the variability of the germ plasm, with its immortality and its eternal transmission? [67] Species and Varieties: their Origin by Mutation, Kegan Paul, London, 1905. [68] Closing sections of Chapter Thirteen. [69] I should like to give an account here of Nicolai's solution of the problem of liberty. He discusses the matter in one of the most important sections of his book.--How can a biologist, filled with a feeling of universal necessity, find place, amid that necessity and without prejudice to it, for human freedom? One of the most notable characteristics of this great mind, is Nicolai's power of associating within himself two rival and complementary forces. He makes a suggestive study, at once philosophic and physiological, of the anatomy of the brain and of the almost infinite possibilities the brain holds for the future (all unknown to us to-day), of the thousands of roads which are marked out in the brain many centuries before humanity dreams of using them.--But to follow up this study would lead us beyond the scope of the present article. I must refer the reader to pp. 58-68 of _The Biology of War_ [English edition]. These pages are a model of scientific intuition. [70] Chapter Ten, p. 309 [English edition]. [71] Chapter Fourteen. [72] Chapter Ten, pp. 270-271 [English edition]. [73] Introduction, p. 11 [English edition]. [74] "Um dem guten und gerechten Menschen meine triumphierende Sicherheit zu geben." Introduction [p. 10, English edition].