The work lit up at once a flame of controversy that has hardly yet diminished in Germany. Students have told me how, when some professor dropped the well-known name in the course of his lecture, the class would split at once into two demonstrative sections. Ten thousand copies of the library edition of the work were sold within a few months, and it quickly ran to eight editions. This remarkable success irritated his opponents, and the wide range of the subjects touched in the work gave them opportunities. Germany was deluged with pamphlets of offence and defence. Some of Haeckel’s pupils replied to his opponents, but the master himself smiled through the storm. His chief critics were men with no competence in biology, and he was not minded to comply with their stratagem of withdrawing attention from the substantial positions of the work. Dennert, the philologist, swept together all the hard sayings about Haeckel that the fierce struggle of the preceding twenty years had produced—Paulsen and Adickes, the metaphysicians, poured philosophic scorn on his pretensions to construct a theory of knowledge. Adickes, in particular, met him with a vigorous fusillade of pure Kantism. It is a curious commentary on this long philosophic disdain to find Haeckel awarded a prominent place amongst “the philosophers since Kant.” Two points in this connection are noteworthy. Haeckel’s first sin against the ruling metaphysic of the nineteenth century was his “naïve realism.” He had dared to think he could break beyond the charmed circle of our states of consciousness. He had dreamed that a real material world lay here in space before the human mind came into existence; that a living, palpitating humanity, not a bloodless phantasm in the mind, called for our most solemn efforts. Where the ordinary reader saw a truism the metaphysicians recognised a deadly sin, and laughed Homeric laughter. To-day we have, both in England and Germany, a strong claim arising amongst the metaphysicians themselves for a return to a realist basis. Haeckel’s second and chief sin was his claim to have thrown light on the evolution of consciousness and his disdain of all study of mind that was not grounded on evolution. To-day Gramzow writes: “The criticism which he makes of Kant’s theory of knowledge from the evolutionary point of view is the greatest advance that philosophy has made in that branch since Kant’s time.”