archetypes are not determined as regards their content, but only as regards their form and then only to a very limited degree… The archetype in itself is empty and purely formal, nothing but a facultas praeformandi
Jung’s canonical definition establishes archetypal form as a purely structural preforming capacity — a possibility of representation given a priori — explicitly distinguished from content, which arises only through conscious experience.
, The Archetypes and the Collective Unconscious, 1959thesis