In a seminal article, J. R. Morgan asserts that the greater part of Heliodorus' Aethiopica explores ‘the antithesis between true love and various corrupt or otherwise unsatisfactory alternatives’. This it does not only through Cnemon's novella, which is narrated mainly in the first two books of the novel, but also through the incident involving the Persian queen Arsake, which to a certain extent replicates Cnemon's story. This narrative duplication is enhanced by the fact that both stories are intertextually related to the myth of Phaedra. Building on Morgan's argument, my contention is that the antithesis between pure love, conditioned by sophrosyne, and illicit desire permeates the entire novel and does not exclusively concern the primary couple or the persons involved in the abovementioned episodes, but relates to almost all the main characters. More importantly, it is precisely this antithesis that constitutes the most fundamental component of the work's structural principle or thesis.