[Humboldt as mediator: Schleiden and Mohl contra Liebig]

Justus Liebig's book Die organische Chemic in ihrer Anwendung auf Agricultur und Physiologie aroused strong opposition from scientists who felt that they were being attacked. A polarization arose particularly between Hugo von Mohl (1805-1872) and Matthias Jacob Schleiden (1805-1881) on one side, and Justus von Liebig (1803-1873) and his followers on the other side. The debate did not have the character of a purely scientific controversy, however, because social aspects also played a role. Alexander von Humboldt (1769-1859), who held the esteem of both parties, was able to intervene successfully to mediate this conflict. His task appeared at first difficult, but it turned out that both groups had a common enemy, the representatives and followers of the 'Romantic philosophy of nature'. Humboldt, who self-deprecatingly called himself a 'fossil', was forced to recognize that many of his friends and acquaintances, who stood nearer to, or even belonged among the founders of Naturphilosophie, for example, Friedrich Wilhelm Joseph von Schelling (1775-1854) and Johann Bernhard Wilbrand (1779-1846), were also under attack. Although he had earlier been inspired by the concerns and ideas of Schelling's Naturphilosophie, he now distanced himself from them in order to mediate between modern, experimental scientists.