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.
Henri Ellenberger
Henri Frédéric Ellenberger (Nalolo, Barotseland, Rhodesia, 6 November 1905 – Quebec, 1 May 1993) was a Canadian psychiatrist, medical historian, and criminologist, sometimes considered the founding historiographer of psychiatry. Ellenberger is chiefly remembered for "The Discovery of the Unconscious", an encyclopedic study of the history of dynamic psychiatry published in 1970.