The reception of Wagner’s music as physically affecting, sound that manipulates the bodies of listeners, took place within a context of research into human and animal physiology. From reflex mechanisms to sense energies, the physiological response to art brought about new understandings of ‘physiological aesthetics’ in figures from Herbert Spencer to Thomas Huxley and Francis Galton, with a corresponding ‘physiological music theory’ applied by Ernst Mach and Hermann von Helmholtz. This led to various efforts at quantification of ear acuity and the role of the auditory nerve.

In the shadow of decadence, critical evaluation of works like Tristan and Tannhäuser traverse the spectrum from appreciation (‘bliss of the spinal cord’) to anxiousness (‘Wagner increases exhaustion’). Against these claims, Wagner’s numerous writings on sentience (Sinnlichkeit), rooted in Ludwig Feuerbach’s philosophy of perceptual realism, were directed towards topics as diverse as a theory of performance, the role of critics, and animal testing.

As psychology emerged as a discipline in the nineteenth century, advances were made in the understanding of the nervous system. The specific functions of nerve fibers were described by Bell and Magendie. Müller’s analysis of neural conduction led Du Bois-Reymond and Helmholtz to describe the nerve impulse. As a reaction against Gall’s phrenology, localization of brain functions reached systematic description by Flourens and Sherrington. Concurrently, advances in physics led to experimental studies of sensations by Young, Helmholtz, and Müller, while Purkinje justified subjective sensory experience. The second intellectual backdrop to psychology was psychophysics, which proposed that sensory experience is not completely reducible to physics and physiology. Although Weber contributed both methodologically and substantively to psychophysics, its clearest expression is found in the quantitative analysis of Fechner. His work received strong support from the experiments of Helmholtz, especially in his doctrine of unconscious inference in perception. The final movement was centered on Darwin’s theory of evolution by natural selection, which completed the Copernican revolution in science and established the primacy of scientific empiricism. Spencer applied Darwin’s writings to evolutionary associationism, and Galton made an intensive examination of individual differences through mental testing. All three movements demonstrated the efficacy of empirical science.