One approaches the inner life of a man like Müller with a certain timidity, and asks how he became what he was. There can be no question that the fundamental trait of his character was a peculiarly deep religious feeling. At heart he was a mystic. The whole magic of his personal influence sprang from these depths. By profession he was a physiologist, an exact scientist. Never did he swerve a hair’s breadth from the iron laws of research. But beneath it all was a suppressed glow of fervour. Every one who understood him, every one who was a true pupil of his, learned it by a kind of hypnotism. Externally he was all for laborious investigation, whether in dissecting a star-fish for you or classifying fishes—though he would have a full sense of your ardent longing for an inner trust in life and a philosophy of life. Both elements might change considerably in the pupil: the method of investigation without—the ideal of the comprehensive vision within. But what never left any man who had followed Müller was the warning cry that these things, within and without, should go together; that, in the larger sense, it is not possible to count the joints in the stalk of an encrinite without feeling a thrill in the deepest depth of the mind and the heart. It is so common a spectacle in history for disciples to condemn their masters with cold smiles that we forget how pitiful it is. No pupil of Johannes Müller has ever felt that he had done with him, and might quit him with ingratitude. He had pupils, it is true, who did not lack belief in themselves, and who became famous enough to give them a sense of power; men who have eventually come to conclusions diametrically opposed to those that Müller had taught them. Yet they respect him. Living witnesses still tell of the glance that bored into you, and could not be evaded. But there must have been a greater power in the man than this piercing glance. It was a glance that survived the grave, and laid on one a duty; a glance that shot up in the darkness of memory if the duty was not fulfilled—the duty of going to the foundation of things. Whether you are examining the larva of an echinoderm or the light of a distant star, God is there. Whether you explain your echinoderm-larva in this way or that; whether you believe your star to be a sun or a burnt-out cinder; whether you conceive God in this way or another—you shall feel that the bridge is there in absolutely everything. Every glance into the microscope is a service of God. It was Goethe’s deepest sun that threw a great, radiant spark out of this curious, dark, angular, unintelligible jewel. Such a man was bound to be more than Kölliker, Virchow, and Gegenbaur to Haeckel. Müller was still teaching at Berlin, and Haeckel’s best star brought him to sit in reality at the feet of the great teacher, who could so well speak soul to soul to him.