The subject of this paper (originally written as a lecture and given at Harvard and Yale in March 1970) may seem a far cry from the main theme of the present volume. Yet it is beyond dispute that the culture of the fifth century b.c. in Greece was still heavily affected by myth, whether as a traditional framework for poetry and drama or as an intellectual force to be combated by Sophists or as a firmly established store of exempla for practical and moral life. In fact it is doubtful whether any other western society is known in which traditional mythology played so great a role. Perhaps the predominant function of the old myths in an age of increasing rationalism was as a categorial structure that provided a set of familiar points of reference against which other ideas and interpretations could be measured. So far, so good; but how far is the accurate discrimination of the primary functions of myths, the main subject of the pages that follow, relevant to the developed uses and schematized forms of myths in the Classical era? It would be misleading to claim more than an indirect connection; yet two brief generalizations may be to the point. First, fifth-century attitudes to the truth of myths varied from incredulity to uncritical belief; but what we need to perceive more clearly, if possible, is the emotional tone or aura evoked by the myths for educated Greeks – something that does not clearly emerge from the literature, and that makes the reactions of Euripides, in particular, very hard to assess.