W. B. Yeats is a poet very much in the line of the English Romantics, for whom what matters most in poetry is the imagination, because they think that without it poetry is impossible. What we call 'the Romantic imagination' seems to have inherited primarily from Plato's idea on the imagination; his idea is that the imagination is a kind of power of memorizing the ideal world before our souls passing over, Lethean River - anamnesis. For him it would be the Joyful Memory of Past, which Wordsworth calls 'Surprised by Joy'. Unfortunately, however, in the Romantic poetry the Platonic Memory would not be described so clearly and so often, because 'the Covering Cherub' some remorse or the negative memory of Freudian past would block the imagination; they had suffered from what would be equated with self-contempt, which destroys the imagination; they had struggled with it as an ultimate antagonist to the Romantic imagination. Yeats as the last Romantic had wished for his proccessor's imagination, having suffered from the same negative stuff. But his poetic unique is that he not only had accepted his own remorse, the negative power to the imagination as his fate, but also had been willing to take advantage of it as a creative and positive power. It would be a single characteristic that differentiates his imagination from the English Romantics's one. It would be what made Kenzaburo Oe feel spiriitual affinity with him and move so much enough to write a 'trilogy', entitled 'A Flaming Green Tree', which is indebted for this title to a stanza from one of Yeats's important poems, 'Vacillation'. (He even calls himself 'a humble follower of Yeats'.) Oe is the novelist who attaches the importance to the imagination, though this attachment comes from the different sources from the English Romantics. He as well as Yeats has suffered from the negative memory which blocks the imagination. It is supposed that he has found the great way to live with the remorse, as 'a friend of his life' in Yeats's poetry. The purpose of this paper is to make clear how Oe has accepted Yeats's way to deal with it through analyzing 'Vacillation' and his trilogy.