Deep within human beings is an innate drive to embrace and actualize the whole of who they are. Given proper nurture, a person develops with the power and direction of a growing seed, synthesizing emergent abilities, acquired skills, and life experiences into a whole, coherent expression of oneself in the world.
The recognition of this impulse stands at the very beginnings of Western depth psychology. Sigmund Freud saw that "psycho-synthesis" within the personality was so fundamental that it need not be addressed directly but would operate naturally if obstacles were removed; Alfred Adler described a basic striving toward wholeness and an "ideal end form" present in both the human and natural worlds; and C.G. Jung wrote of the unification and transformation of the personality initiated by a deeper Self beyond the conscious ego.
The Italian psychiatrist Roberto Assagioli, a contemporary of these thinkers, placed the process of synthesis at the very center of the psychology called psychosynthesis. By psychosynthesis he meant a movement toward organization, coherence, and harmony within the human personality, among individuals, and among human groups. He, with Jung, recognized a deeper self as the ultimate source of this process, and, like Adler and later Carl Rogers, saw this process operating in the natural world as well.
-- A Psychotherapy of Love, psychosynthesis in practice, John Firman and Ann Gila