Three major metamorphoses of the motifs and themes of our subject, therefore, have to be recognized as fundamentally differing even though fundamentally related, namely: the true poetry of the poet, the poetry overdone of the prophet, and the poetry done to death of the priest.
Campbell proposes a tripartite metamorphic schema — poet, prophet, priest — as the governing structural law of mythological history, directly invoking the logic of the Three Metamorphoses as a cultural-typological principle.
, Occidental Mythology: The Masks of God, Volume III, 1964thesis