Psychic existence is the only category of existence of which we have immediate knowledge, since nothing can be known unless it first appears as a psychic image. Only psychic existence is immediately verifiable.
Jung argues that ‘psychic reality’ is not merely one ontological region but the sole immediately verifiable form of existence, making the psyche the indispensable sine qua non of all knowledge.
, Psychology and Religion: West and East, 1958thesis