The Gāthic stanza Y 30.3 has always been at the center of various interpretations and controversies in Western scholarship on Zoroastrianism. Those who believe they have discovered in the Gāthās a monotheistic religion armored with an ethical dualism have made this stanza one of the pillars of their thesis. The so-called Twins stanza shows, according to this view, that the good and evil primordial spirits exist as a result of their choice between Good and Evil, which preserves not only the absolute goodness of the supreme god but also his uniqueness. More recently Kellens and others following him have given a completely different reading of the stanza. According to their account, this stanza is a speculation on the hidden processes of ritual. What the poet expresses in Y 30.3 is not a dualism, ethical or otherwise, but a psychology of the process by which man makes his choice of ritual conduct. Aside from the question of coherence, one must ask whether these accounts are borne out by the text they claim as their basis. This article addresses these two questions.