Life.
I was confirmed in this design by the circumstance that another scientist, the botanist Johannes Reinke, of Kiel, had published two works in which he had treated the general problems of natural philosophy, especially of biology, from a purely dualistic and teleological point of view; these works were his Die Welt als That (1899) and Einleitung in die theoretische Biologie (1902). As both these works are well written and present the principles of dualism and teleology with admirable consistency—as far as this is possible—it seemed to me that it was desirable to give a thorough exposition of my own monistic and causative system.
Hence the present work on the wonders of life is, as the title indicates, a supplementary volume to The Riddle of the Universe. While the latter undertook to make a comprehensive survey of the general questions of science—as cosmological problems—in the light of the monistic philosophy, the present volume is confined to the realm of organic science, or the science of life. It seeks to deal connectedly with the general problems of biology, in strict accord with the monistic and mechanical principles which I laid down in 1866 in my General Morphology. In this I laid special stress on the universality of the law of substance and the substantial unity of nature, which I have further treated in the second and fourteenth chapters of The Riddle of the Universe.
The arrangement of the vast material for this study of the wonders of life has been modelled on that of the Riddle. I have retained the division into larger and smaller sections and the synopses of the various chapters. Thus the whole biological content falls into four sections and twenty chapters. I should much have liked to add illustrations in many parts of the text to make the subject plainer, especially as regards chapters vii., viii., xi., and xvi.; but this would have led to a considerable increase in the size and price of the book. Moreover, there are now many illustrated works which will help the reader to go more fully into the various sections of the study. Among others, my History of Creation (English translation) and Evolution of Man (English translation now in course of preparation) will be found helpful in this way. The German reader will also find many illustrations to elucidate the text of this book in my recently completed work, Kunstformen der Natur (10 parts, with 100 tables, 1899–1904).
I had said, in the preface to The Riddle of the Universe in 1899, that I proposed to close my study of the monistic system with that work, and that "I am wholly a child of the nineteenth century, and with its close I draw the line under my life's work." If I now seem to run counter to this observation, I beg the reader to consider that this work on the wonders of life is a necessary supplement to the widely circulated Riddle of the Universe, and that I felt bound to write it in response to the inquiries of so many of my readers. In this second work, as in the earlier one, I make no pretension to give the reader a comprehensive statement of my monistic philosophy in the full maturity it has reached—for me personally, at least—at the close of the nineteenth century. A subjective theory of the world such as this can, naturally, never hope to have a complete objective validity. My knowledge is incomplete, like that of all other men. Hence, even in this "biological sketch-book," I can only offer studies of unequal value and incomplete workmanship. There still remains the great design of embracing all the exuberant phenomena of organic life in one general scheme and explaining all the wonders of life from the monistic point of view, as forms of one great harmoniously working universe—whether you call this Nature or Cosmos, World or God.
The twenty chapters of The Wonders of Life were written uninterruptedly in the course of four months which I spent at Rapallo, on the shore of the blue Mediterranean. The quiet life in this tiny coast-town of the Italian Riviera gave me leisure to weigh again all the views on organic life which I had formed by many-sided experience of life and learning since the beginning of my academic studies (1852) and my teaching at Jena (1861). To this I was stimulated by the constant sight of the blue Mediterranean, the countless inhabitants of which had, for fifty years, afforded such ample material for my biological studies; and my solitary walks in the wild gorges of the Ligurian Apennines, and the moving spectacle of its forest-crowned mountain altars, inspired me with a feeling of the unity of living nature—a feeling that only too easily fades away in the study of detail in the laboratory. On the other hand, such a situation did not allow a comprehensive survey of the boundless literature which has been evoked by the immense advances in every branch of biology. However, the present work is not intended to be a systematic manual of general biology. In the revision of the text, on which I was engaged during the summer at Jena, I had to restrict myself to occasional additions and improvements. In this I had the assistance of my worthy pupil, Dr. Heinrich Schmidt, to whom also I am indebted for the careful revision of the proofs.
When I completed my seventieth year at Rapallo, on February 16th, I was overwhelmed with a mass of congratulations, letters, telegrams, flowers, and other gifts, most of which came from unknown readers of The Riddle of the Universe in all parts of the world. If my thanks have not yet reached any of them, I beg to tender them in these lines. But I should be especially gratified if they would regard this work on the wonders of life as an expression of my thanks, and as a literary gift in return. May my readers be moved by it to penetrate deeper and deeper into the glorious work of Nature, and to reach the insight of our greatest German natural philosopher, Goethe:
"What greater thing in life can man achieve
Than that God-Nature be revealed to him?"
Ernst Haeckel.
Jena, June 17, 1904.
THE WONDERS OF LIFE
THE WONDERS OF LIFE
I
TRUTH
Truth and the riddle of the universe—Experience and thought—Empiricism and speculation—Natural philosophy—Science—Empirical science—Descriptive science—Observation and experiment—History and tradition—Philosophic science—Theory of knowledge—Knowledge and the brain—Æstheta and phroneta—Seat of the soul, or organ of thought: phronema—Anatomy, physiology, ontogeny, and phylogeny of the phronema—Psychological metamorphoses—Evolution of consciousness—Monistic and dualistic theories of knowledge—Divergence of the two ways of attaining the truth.
What is truth? This great question has occupied the more thoughtful of men for thousands of years, and elicited myriads of attempts to answer it, myriads of truths and untruths. Every history of philosophy gives a longer or shorter account of these countless efforts of the advancing mind of man to attain a clear knowledge of the world and of itself. Nay, even "world-wisdom" itself, or philosophy in the proper sense of the word, is nothing but a connected effort to unite the general results of man's investigation, observation, reflection, and thought, and bring them to a common focus. Without prejudice and without fear, philosophy would tear the mantle from "the veiled statue of Sais," and attain a full vision of the truth. True philosophy, taken in this sense, may proudly and justly style itself "the queen of the sciences."
When philosophy, as a search for truth in the highest sense, thus unites our isolated discoveries and seeks to weld them into one unified system of the world, it comes at length to state certain fundamental problems, the answer to which varies according to the degree of culture and the point of view of the inquirer. These final and highest objects of scientific inquiry have been of late comprehended under the title of The Riddle of the Universe, and I gave this name to the work I published in 1899, which dealt with them, in order to make its aim perfectly clear. In the first chapter I dealt briefly with what have been called "the seven great cosmic problems," and in the twelfth chapter I endeavored to show that they may all be reduced to one final "problem of substance," or one great "riddle of the universe." The general formulation of this problem is effected by blending the two chief cosmic laws—the chemical law of the constancy of matter (Lavoisier, 1789), and the physical law