The three daughters of Cecrops[744] are by the time of Euripides ‘maidens threefold’; the three daughters of Erechtheus[745], who are but their later doubles, are a ‘triple yoke of maidens,’ and yet—in the case of the daughters of Cecrops—there is ample evidence[746] that originally they were two, and these two probably a mother and a maid. Aglauros and Pandrosos are definite personalities; they had regular precincts and shrines, known in historical times, Aglauros on the north slope of the Acropolis[747], where the maidens danced, Pandrosos to the west of the Erechtheion[748]. But of a shrine, precinct, or sanctuary of Herse we have no notice. Ovid[749] probably felt the difficulty; he lodges Herse in a chamber midway between Aglauros and Pandrosos. The women of Athens swore by Aglauros and more rarely by Pandrosos[750]. Aglauros, by whom they swore most frequently, and who gave her name to the Agraulids, was probably the earlier and mother-form. Herse was no good even to swear by; she is the mere senseless etymological eponym of the festival of the Hersephoria, a third sister added to make up the canonical triad. The Hersephoria out of which she is made was not in her honour; it was celebrated to Athene, to Pandrosos, to Ge, to Themis, to Eileithyia. The women trinities rose out of dualities, but not every duality became a trinity. Plutarch[751], in discussing the origin of the nine Muses, notes that we have not three Demeters, or three Athenes, or three Artemises. He touches unconsciously on the reason why some dualities resisted the impulse to become trinities. Where personification had become complete, as in the case of Demeter and Kore, or of their doubles, Damia and Auxesia, no third figure could lightly be added. Where the divine pair were still in flux, still called by merely adjectival titles that had not crystallized into proper names, a person more or less mattered little. Thus we have a trinity of Semnae, of Horae, of Moirae, but the Thesmophoroi, who _as_ Thesmophoroi might have easily passed into a trinity, remain always, because of the clear outlines of Demeter and Kore, a duality. When we ask what was the impulse to the formation of trinities, the answer is necessarily complex. Many strands seem to have gone to their weaving. * * * * *