Discusses the dinnshenchas sources used in the ‘riddling colloquy’ of Tochmarc Emire, and argues that the itinerary described in it contains a learned allusion to the Túatha Dé Danann and the Fomóiri, respectively represented by Cú Chulainn and Emer, and their conflict, which is overcome by the marriage between the races, thus explaining why Emer is the only suitable match for Cú Chulainn.