To confuse Being with a being is the metaphysical catastrophe. It is the ‘death of Being’ to confuse the unity of Being (Esse) with a pseudo-unity of beings (ens) which is essentially multiple.
Corbin, via Miller, furnishes the term’s canonical definition: the metaphysical catastrophe is the ontological error of collapsing Being into a supreme being, an error he identifies as constitutive of official monotheism and destructive of the mystery of Esse.
, The New Polytheism: Rebirth of the Gods and Goddesses, 1974thesis