 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.