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.

Chapter 4 synthesizes the concerns of the first three chapters. It is about four topics that underlie the Anthropocene: gradients (the way qualities vary in their intensity over space and time, and the ways such variations relate to causal processes); grading (the ways agents assess and alter such intensities and experience and intervene in causal processes); degradation (the ways highly valuable variations in qualitative intensities are lowered or lost); and grace (the way agents work to maintain gradients, care for those whose lives have been degraded, and value those agents who work and care in such ways). It reframes a few universal thermodynamic variables as (soon to be, if not already) global sociocultural values: energy, entropy, work, and temperature. In addition, it details some of the key features of one important nineteenth-century cosmology in regard to the origins of the Anthropocene (and the discipline of anthropology).