He subsequently trained as an analyst and psychiatrist, during which time he developed the concepts and theory of psychosynthesis.   At the beginning of the 20th century there was an uprising of exciting ideas in all areas of thought. Influences from the East were beginning to come over to the West and therefore religious thought was being reexamined, education was being revolutionised with such thinkers as Montessori, Froebel and Steiner, and the unconscious was being scientifically studied by Freud, among others.

This was therefore very much a Renaissance time and accordingly Assagioli drew from many fields and influences, though he tended to play down the more mystical aspects of his work, intending to gain scientific validity for his theories.  Inherent in the development of his ideas are both a scientific and a mystical approach.