Gustav Fechner
Fechner, along with Wilhelm Wundt and Hermann von Helmholtz, is recognized as one of the founders of modern experimental psychology. His clearest contribution was the demonstration that because the mind was susceptible to measurement and mathematical treatment, psychology had the potential to become a quantified science. Theorists such as Immanuel Kant had long stated that this was impossible, and that therefore, a science of psychology was also impossible.
The Discovery of the Unconscious
The Discovery of the Unconscious: The History and Evolution of Dynamic Psychiatry is a 1970 book by the Swiss medical historian Henri F. Ellenberger. In this study of the history of dynamic psychiatry, Ellenberger provides an account of the early history of psychology covering such figures as Franz Anton Mesmer, Sigmund Freud, Carl Jung, Alfred Adler, and Pierre Janet. The work has become a classic, and has been credited with demolishing the myth of Freud's originality and encouraging scholars to question the scientific validity of psychoanalysis. Critics have questioned the reliability of some of Ellenberger's judgments.