be remembered that he was primarily a physiologist, not a metaphysician. Matter and force (or energy) are, he maintained, infinite; the conservation of force follows from the imperishability of matter, the ultimate basis of all science. Büchner is not always clear in his theory of the relation between matter and force. At one time he refuses to explain it, but generally he assumes that all natural and spiritual forces are indwelling in matter. Just as a steam engine, he says in Kraft und Stoff (7th ed., p. 130), produces motion, so the intricate organic complex of force-bearing substance in an animal organism produces a total sum of certain effects, which, when bound together in a unity, are called by us mind, soul, thought. Here he postulates force and mind as emanating from original matter, a materialistic monism. But in other parts of his works he suggests that mind and matter are two different aspects of that which is the basis of all things, a monism which is not necessarily materialistic. Büchner was much less concerned to establish a scientific metaphysics than to protest against the romantic idealism of his predecessors and the theological interpretations of the universe. Nature according to him is purely physical; it has no purpose, no will, no laws imposed by extraneous authority, no supernatural ethical sanction. Büchner endorsed Charles Darwin's theory of evolution within a decade of its first issuance, writing the book Man in the Past, Present and Future in 1869 about what he felt were Darwinism's implications. He believed that this included humanity moving into a kinder state of being, where a primitive struggle for life would no longer apply or at least be replaced with purely intellectual struggles, and war would end. To achieve this, Büchner advocated government social programs which would aid greater equality, including the collective ownership of land and women's rights (however he did not extend this to them receiving suffrage, deeming that premature at the time). Büchner, together with Edward Aveling, had attended the congress of the "International Federation of Freethinkers" held in London from 25 to 27 September, the following day they visited Darwin on 28 September. Aveling published a full account of his visit in the National Reformer in 1882. Modern Christian apologists consider Büchner the father of atheistic evangelism in Germany, a counterpart to Thomas Huxley. Ludwig Büchner was the brother of Georg Büchner, a famous