 However, in 1824, the very year in which Stapelia mixta appeared, Fechner seemed to have lost further confidence in Naturphilosophie. In that year he had begun to translate the French physicists Louis Jacques Thénard (1777–1857) and Jena Baptiste Biot (1774–1862), whose work deeply impressed him (Thénard 1813–16 [trans. 1825–28] and Biot 1817 [trans. 1828–29]). By following careful methods of experimentation and observation, the French physicists seemed to produce definite results. Fechner asked himself if Oken and Schelling could ever have produced the precise laws of optics found in Biot’s work? (Kuntze 1892: 39–40). 