His academic colleagues had hardly begun to master this new phylogeny when Haeckel once more roused a general agitation by working up the philosophic nucleus of the Morphology in a more general form than he had done in the History of Creation. This new work was The Riddle of the Universe, “a popular study of the Monistic philosophy.”^[8] It was, he declared, his philosophical testament. In a few months 10,000 copies of the work were sold, and a later cheap popular edition ran to more than 100,000 copies. It has also been translated into fourteen different languages. The controversy it excited has not yet died away. Already a supplementary volume, The Wonders of Life, has followed it (1904). Haeckel had been working in this department with great vigour for many years. He only made one appearance at a German scientific congress since the Virchow affair. That was on September 18, 1882, in quiet and uncontroversial form. A little excitement was caused amongst those who saw their salvation in keeping the gentle Darwin far apart from the impetuous Haeckel when he read a rather free philosophical confession of Darwin’s. Their tactics broke down as the deceased Darwin passed into an historical personality and disappeared from the struggle of contending parties. In 1892 Haeckel wrote with great vigour in the militant Berlin journal, the Freie Bühne, on the new alliance of the Church and political parties in Germany, criticising the political situation on general philosophical principles, and in opposition to Virchow’s spirit of compromise. In the same year he delivered at Altenburg a lecture on “Monism as a connecting link between religion and science.” In this he took a conciliatory line, and showed how his philosophic views could be reconciled with any really sincere pursuit of truth, whatever aim it professed to have. The address closed with the words: “May God, the spirit of the good, the beautiful, and the true, grant it.” However, both his criticism and his attempt at conciliation only led to further and more bitter attacks in certain quarters. His only reply was to bring out the first numbers of a fine illustrated work—a work that came from a quite different depth of his rich personality. This was the Art-forms in Nature [not translated], a collection of beautiful forms of radiolaria, sponges, siphonophores, &c., for artists and admirers of the beautiful. It was a work such as he alone could produce. “In the storm didst thou begin: in the storm shalt thou end,” he might have said to himself, in the words of David Strauss. The storm never left him. In its mood was flung off with ready pen the Riddle of the Universe. “Up, old warrior, gird thy loins!” as we read in Strauss.

The biographical sketch of a living man does not close with a stroke, but with three stars. They glow still, these stars. Under their influence much may yet happen—much struggle, much peace. In view of the general situation of our time there is little hope that the last stretch of this extraordinary career will be spent in peace, though behind it all lies the peace-loving soul of an artist. But if Haeckel’s career is to be one of struggle to the last hour, he may console himself with the noble words of Goethe:—