What is the basis of our insight into the fundamental identity of Demeter and Persephone? It is based on psychic reality and on the tradition that testifies to the existence of this psychic reality in antiquity.
Kerényi, citing Jung, argues that the mother–daughter pair constitutes a single psychic reality, their apparent duality resolving into a fundamental identity attested by the Eleusinian cult.
, Essays on a Science of Mythology: The Myth of the Divine Child and the Mysteries of Eleusis, 1949thesis