As part of the part aesthetic, part political effort to forge the Irish character through literature, Yeats and his peers drew material directly from the ancient myth cycles of the pre-Christian Celts, and infused their poetry and drama with the heroic characters and ethos, and sometimes the language, of the time before the British invasion and occupation of Ireland.
Hence, Yeats’ invocation of the Rose in a manner reminiscent of the ancient Greek and Roman poets’ invocation of the muses to aid in the composition of the epics of their race. So Yeats asks the rose to be near “while I sing the ancient ways”, and as he recalls the mythic figures in the reconstitution of his race.
The Druid stands as a general symbol of the Celtic world ethic before the Christian missionizing; Cuchulain is an Achilles-like hero who single handedly defeats many of the enemies of his people before succumbing to his own weaknesses battling against the sea; Fergus is a mythic king of Ulster and symbol of the golden age of Gaelic civilization.
Personally, the rose symbolizes the figure of, and his undying — though unrequited — love for Maud Gonne, at once a personal love and a realization of his vision of Romantic Irish womanhood. It is therefore fitting to learn that “the conjoined rose and cross” (“the rose upon the rood of time”) also “symbolised a mystic marriage”, according to A. Norman Jeffares, in his edition of Yeats’ selected poems.
In all this, Yeats wants to discover behind the edifice of all the “poor foolish things...