To illustrate what he meant by the non-psychic or ‘psychoid’ aspect of the archetype, Jung drew an analogy with the electromagnetic spectrum. The part of the spectrum which is visible to us (i.e., the ultra-violet end) represents those psychic processes of which we are conscious. The invisible infra-red end of the spectrum corresponds to the unconscious biological aspect of the archetype which is identical with ‘the physiology of the organism and thus merges with its chemical and physical conditions’ (1947/1954: par. 420).
CW 8 On the nature of the psyche
