 While Helmholtz did not contradict Müller by name in his writings on physiology, Helmholtz’s research, in Müller’s and Magnus’s labs and later in his own labs in Bonn and Königsberg, is in conflict with the doctrine of specific sense energies (see Otis 2007, 129–130). Helmholtz proposes a “sign” theory, according to which sensations symbolize their stimuli, but are not direct copies of those stimuli. While Müller explains the correspondence between sensation and object by means of an innate configuration of sense nerves, Helmholtz argues that we construct that correspondence by means of a series of learned, “unconscious inferences.” 