Like all archetypal symbols, the symbol of the tree has undergone a development of meaning in the course of the centuries… The psychoid form underlying any archetypal image retains its character at all stages of development, though empirically it is capable of endless variations.
Jung establishes that archetypal symbols possess a stable psychoid substrate while manifesting in historically variable forms, articulating the essential duality of constancy and transformation.
, Collected Works Volume 3: The Psychogenesis of Mental Disease, 1907thesis