By saying the breath Agamemnon breathed was ‘of his phren,’ Aeschylus hands us in a single phrase the ambivalence of tragic causality. The chorus does not say Iphigeneia’s death was only Agamemnon’s fault.
Padel argues that Aeschylus’s precise formulation of Agamemnon’s ‘breath of the phren’ deliberately encodes the irreducible ambiguity between internal moral agency and external compulsion that defines tragic causality in the Oresteia.
, In and Out of the Mind Greek Images of the Tragic Self, 1994thesis