accretions of untold centuries of ancestral life, the unconscious psyche must consist of inherited instincts, functions, and forms that are peculiar to the ancestral psyche.
Jung’s most explicit definitional statement of the ancestral psyche, identifying it as the structural inheritance of instincts, functions, and forms rather than transmitted ideas, and equating it with the matrix of archetypal conditions.
, Collected Works Volume 16: The Practice of Psychotherapy, 1954thesis