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.
Thomas Cogswell Upham
Thomas Upham (January 30, 1799 – April 2, 1872) was an American philosopher, psychologist, pacifist, poet, author, and educator. He was an important figure in the holiness movement. He became influential within psychology literature and served as the Bowdoin College professor of mental and moral philosophy from 1825-1868. His most popular work, "Mental Philosophy" received 57 editions over a 73-year period. Additionally, he produced a volume of 16 other books and the first treatise on abnormal psychology, as well as several other works on religious themes and figures. Specific teachings included a conception of mental faculties - one of these restoring the will to psychology be developing a tripartite division of mental phenomena into intellectual, sentient, and voluntary. The intellect subsumed sensation and perception, attention, habit, association, and memory as well as reasoning. Sensibilities included natural emotions and desires, such as appetites, propensities, and affections, and also moral emotions, such as a feeling of obligation. Finally, the last division was the will, which allowed for volition as a basic component of human nature. This positing of a will free to choose between desires and obligations reflected the author's own spiritual journey from a Calvinistic background to the Wesleyan holiness perspective. However, perhaps his most critical contribution to the field of psychology was Upham's concept of Positive psychology which asserts that there are fundamental, transcendent laws, and living in harmony with them is the key to mental and spiritual health. This concept laid the foundation for a healthy kind of religiosity, and a spiritually-based positive psychology.