The time seems to have come in England for the publication of some authoritative picture of the great biologist and controversialist. One work of his circulates by the hundred thousand amongst us, and has had a deep and lasting influence on the thoughts of large classes of men. His influence is hardly less in France and Italy, as well as in Germany; his doctrines have, in fact, been translated into fifteen different tongues. The deep, sometimes bitter, controversy that they have engendered must have led to a desire to know more of the man and his making. The attempts that have been made here and there to “construct” him from his ideas and literary manner are, as the reader will see, very far removed from the reality. Behind all the strained inferences from doctrines, behind all the dishonouring epithets, there is a genial, warm, deeply artistic, intensely idealist nature, sung with enthusiasm by poets who have known him. Once, in playful scientific mood, Haeckel tried to explain his own character in his familiar terms of heredity and environment. He came of a line of lawyers, straight, orderly, inexorable men. He had lived and worked in quiet Jena, in the beautiful valley of the Saale. But he did not speak of that larger environment—the field of battle, stretching far away, beyond the calm Thuringian hills, to the ends of Europe. We must place Haeckel’s ardent and high-minded nature in that field, face to face with his opponents, if we would understand him. For the supplementary chapter I have drawn freely on another biographical sketch by one of Haeckel’s pupils, Dr. Breitenbach, and other sources. For the illustrations I am indebted chiefly to Professor Haeckel himself, and can only offer him in return this grateful effort to lift his inspiring and impressive personality above the dust and cloud of a great controversy. JOSEPH McCABE. ------------------------------------------------------------------------ CHAPTER I EARLY YOUTH “I am wholly a child of the nineteenth century, and with its close I would draw the line under my life’s work.” Thus does Professor Haeckel speak of himself. There is a note of gentle resignation in the words, but the time is coming when men will give them a different meaning. Whatever greater achievements may be wrought by a future generation in the service of truth and human welfare, their work will be but a continuation of the truth of our time, as long as humanity breathes. On the intrepid, outstanding figures of the nineteenth century will shine a light that is peculiarly theirs, an illumination that men will dwell on for ever—as we look back, in personal life, on the young days of love. It was a strong love that brought our century to birth. The soul of humanity has for four centuries been passing through a grim crisis.