The _Evolution of Man_ not only offers the complete proof of its thesis—a proof accepted by every prominent biologist in England and by many prelates (such as the Bishop of London and the Dean of Westminster)—but affords also interesting proof of Haeckel’s artistic gifts. Some of the best plates in the work are executed by him. But in the same year, 1903, he gave a more popular evidence of it. In detached numbers he published the large and beautiful volume of his _Art-forms in Nature_. In this work he depicts with remarkable success hundreds of the most beautiful forms that his long study of marine life had brought before him. A fine expression of the man’s dual nature, the work appeals with equal force to the æsthete and the scientist. And during the long hours that he was peering into his microscope and sketching the delicate and graceful forms, the din and roar of the mighty controversy he had aroused was breaking in with every post. By the end of the year he had received more than 5,000 letters in connection with the _Riddle of the Universe_. Scurrilous letters and idolatrous letters, sober letters and fantastic letters, flowed upon the Zoological Institute, where he worked with pen and pencil, and were duly read. He merely defended himself by posting to each correspondent a printed form that he would soon issue a new work in which the further questions would be answered. He had given his life to science and humanity, and would not withdraw for the well-earned rest. And from a thousand pulpits over Europe and America the aged and self-sacrificing worker was being denounced and caricatured to audiences who had not the remotest knowledge of his aims and his work. A friend of mine heard a minister in an important Glasgow church assure his congregation from the pulpit that “Haeckel was a man of notoriously licentious life;” he had heard it “from a friend of Haeckel’s.” At the very time when Haeckel was buried in his splendid artistic work, the _Christian World Pulpit_ was issuing a sermon in which Dr. Horton was explaining “the personal factor” in Haeckel. “He is an atrophied soul, a being that is blind on the spiritual side,” the popular preacher declared.