THE RIDDLE OF THE UNIVERSE EttNBT HAECKEL THE RIDDLE OF THE UNIVERSE AT THE CLOSE OF THE NINETEENTH CENTURY BY ERNST HAECKEL Ph. D., M. D., LL. IX, Sc. B., and Professor at the University of Jena AUTHOR OF THE HISTORY OF CREATION THE EVOLUTION OF MAN ETC. TRANSLATED BY JOSEPH McCABE HARPER BROTHERS PUBLISHERS . NEW YORK AND LONDON I QOI CONTENTS PAGB AUTHORS PREFACE v TRANSLATORS PREFACE xi CHAPTER I THE NATURE OF THE PROBLEM i CHAPTER H OUR BODILY FRAME 22 CHAPTER HI OUR LIFE 39 CHAPTER IV OUR EMBRYONIC DEVELOPMENT 53 CHAPTER V THE HISTORY OF OUR SPECIES 71 CHAPTER VI THE NATURE OF THE SOUL 88 CHAPTER VH - PSYCHIC GRADATIONS 108 CHAPTER VIII THE EMBRYOLOGY OF THE Sora 132 CHAPTER IX THE PHTLOGENY OF THE SOUL 148 iii CONTENTS CHAPTER X PAGB CONSCIOUSNESS 170 CHAPTER XI THE IMMORTALITY OF THE SOUL 188 CHAPTER XII THE LAW OP SUBSTANCE 211 CHAPTER XIH THE EVOLUTION OF THE WORLD 233 CHAPTER XIV THE UNITY OF NATURE 254 CHAPTER XV GOD AND THE WORLD 275 CHAPTER XVI KNOWLEDGE AND BELIEF 292 CHAPTER XVII SCIENCE AND CHRISTIANITY 308 CHAPTER XVIII OUR MONISTIC RELIGION 331 CHAPTER XIX OUR MONISTIC ETHICS 347 CHAPTER XX SOLUTION OF THE WORLD-PROBLEMS 365 CONCLUSION 380 INDEX AUTHORS PREFACE TTHE present study of the monistic philosophy is intended for thoughtful readers of every condi tion who are united in an honest search for the truth. An intensification of this effort of man to attain a knowledge of the truth is one of the most salient features of the nineteenth century. That is easily ex plained, in the first place, by the immense progress of science, especially in its most important branch, the history of humanity it is due, in the second place, to the open contradiction that has developedduring the century between science and the traditional Rev elation and, finally, it arises from the inevitable ex tension and deepening of the rational demand for an elucidation of the innumerable facts that have been recently brought to light, and for a fuller knowledge of their causes, Unfortunately, this vast progress of empirical knowl edge in our Century of Science has not been ac companied by a corresponding advancement of its theoretical interpretation that higher knowledge of the causal nexus of individual phenomena which we call philosophy. We find, on the contrary, that the abstract and almost wholly metaphysical science which has been taught in our universities for the AUTHORS PREFACE last hundred years under the name of philosophy is far from assimilating our hard-earned treasures of experimental research. On the other hand, we have to admit, with equal regret, that most of the repre sentatives of what is called exact science are con tent with the special care of their own narrow branches of observation and experiment, and deem superfluous the deeper study of the universal connection of the phenomena they observe that is, philosophy. While these pure empiricists do not see the wood for the trees the metaphysicians, on the other hand, are satis fied with the mere picture of the wood, and trouble not about its individual trees. The idea of a philosophy of nature to which both those methods of research, the empirical and the speculative, naturally converge, is even yet contemptuously rejected by large numbers of representatives of both tendencies. This unnatural and fatal opposition between science and philosophy, between the results of experience and of thought, is undoubtedlybecoming more and more onerous and painful to thoughtful people. That is easily proved by the increasing spread of the immense popular literature of natural philosophy which has sprung up in the course of the last half-century. It is seen, too, in the welcome fact that, in spite of the mutual aversion of the scientific observer and the speculative philosopher, nevertheless eminent thinkers from both camps league themselves in a united ef fort to attain the solution of that highest object of in quiry which we briefly denominate the world-riddles…