BÜCHNER, Ludwig. - German philosopher, born in Darmstadt on March 29, 1824, died there on May 1, 1899. A physician, he was influenced by Moleschott and became one of the most illustrious popularizers of materialism. His work *Kraft und Stoff* (1855) achieved extraordinary success and served as the breviary of the new philosophical movement throughout the second half of the 19th century; between 1855 and 1889 it went through 16 German editions and numerous translations. The scandal it provoked cost him his university chair, after which he returned to practicing medicine in his hometown. B.'s system is of elementary simplicity: everything reduces to matter and force, eternal elements that, when combined, form the sum of the phenomena we call the world. All energies, even those termed spiritual, reside in matter; it must therefore be considered the original foundation of all existence.
In addition to *Kraft und Stoff*, B. wrote *Natur und Geist* (Leipzig 1876); *Der Mensch und seine Stellung in der Natur* (ibid. 1889); *Das goldene Zeitalter oder das Leben in der Geschichte* (Berlin 1891); *Darwinismus und Sozialismus* (ibid. 1894); etc.