Thomas Huxley, known as “Darwin’s Bulldog” for his championing and development of Darwinism, was perhaps the most important Victorian biologist after Darwin himself. This speech to the Metaphysical Society in 1870 is one of Huxley’s best known texts outside the sphere of his specialism, and remains read today by students of philosophy. In it, Huxley argues from the results of vivisection to metaphysics.