"He is a philosopher and a metaphysician, and one of the most advanced scientists of his day... this, with an iron nerve, a temper of the ice-brook, and indomitable resolution, self-command, and toleration exalted from virtues to blessings, and the kindliest and truest heart that beats, these form his equipment for the noble work that he is doing for mankind, work both in theory and practice, for his views are as wide as his all-embracing sympathy."