The elementary, or innate, ideas we must interpret, I believe, as a reference, in nineteenth-century terms, to what now would be called the innate neurological structures (CEMs and IRMs) of the biological species Homo sapiens
Campbell argues that Bastian’s elementary ideas are most precisely understood as the inherited neurological structures of the human nervous system, providing a biological reinterpretation of a nineteenth-century ethnological concept.
, Primitive Mythology (The Masks of God, Volume I), 1959thesis