Throughout this discussion of the riddles of the universe I have clearly defined my consistent monistic position and its opposition to the still prevalent dualistic theory. In this I am supported by the agreement of nearly all modern scientists who have the courage to accept a rounded philosophical system. I must not, however, take leave of my readers without pointing out in a conciliatory way that this strenuous opposition may be toned down to a certain degree on clear and logical reflection--may, indeed, even be converted into a friendly harmony. In a thoroughly logical mind, applying the highest principles with equal force in the entire field of the cosmos--in both organic and inorganic nature--the antithetical positions of theism and pantheism, vitalism and mechanism, approach until they touch each other. Unfortunately, consecutive thought is a rare phenomenon in nature. The great majority of philosophers are content to grasp with the right hand the pure knowledge that is built on experience, but they will not part with the mystic faith based on revelation, to which they cling with the left. The best type of this contradictory dualism is the conflict of pure and practical reason in the critical philosophy of the most famous of modern thinkers, Immanuel Kant. On the other hand, the number is always small of the thinkers who will boldly reject dualism and embrace pure monism. That is equally true of consistent idealists and theists, and of logical realists and pantheists. However, the reconciliation of these apparent antitheses, and, consequently, the advance towards the solution of the fundamental riddle of the universe, is brought nearer to us every year in the ever-increasing growth of our knowledge of nature. We may, therefore, express a hope that the approaching twentieth century will complete the task of resolving the antitheses, and, by the construction of a system of pure monism, spread far and wide the long-desired unity of world-conception. Germany's greatest thinker and poet, whose one hundred and fiftieth anniversary will soon be upon us--Wolfgang Goethe--gave this "philosophy of unity" a perfect poetic expression, at the very beginning of the century, in his immortal poems, _Faust_, _Prometheus_, and _God and the World_: "By eternal laws Of iron ruled, Must all fulfil The cycle of Their destiny." FOOTNOTES: [1] There are two English translations, _The Evolution of Man_ (1879) and _The Pedigree of Man_ (1880). [2] The English translation, by Dr. Hans Gadow, bears the title of _The Last Link_. [3] English translation, by J. Gilchrist, with the title of _Monism_. [4] E. Haeckel, _Systematische Phylogenie_, 1895, vol. iii., pp. 646-50. (Anthropolatry means "A divine worship of human nature.") [5] Cf. my Cambridge lecture, _The Last Link_, "Geological Time and Evolution." [6] As to induction and deduction, _vide_ _The Natural History of Creation_.