There has been no dearth, since Plutarch’s day at least, of erudite theories about what message the E at Apollo’s temple was meant to convey to visitors. Yet no account so far has added up to a truly compelling answer, not for lack of ingenuity, but because the various approaches have tended so strongly towards the sophisticated and artful, rather than the probable. This article will review why the familiar answers are more impressive than convincing, and will propose in their place a much simpler explanation: namely that the E was meant to represent the mysterious itself, reminding pilgrims that they were entering a realm where logos continued to hold sway, to be sure, as the other inscriptions testified, but where the human intellect must leave room for mantic wisdom, and where logical reasoning must be supplemented with contemplation and meditation upon the enigmatic, the hidden, and the ineffable.