Declan Kiberd at The Dublin Review of Books:
Yeats saw so deeply into the contours of his age that the shape of the future became somewhat discernible. He understood that those who merely reflect the nostra of their times soon go out of fashion (“like an old song”), but that those who oppose the spirit of their age often capture its central energies and come to know it from within. In doing as much, they may imagine the sort of future world to which a dreamer will awaken (“In dreams begin responsibility”).
Hence the exactitude of the title Yeats Now. He may be a poet for all time, but his wisdom is surely needed in our time. Eliot said that he was one of those who had such insights into the modern age that it could not be understood without them. Having early become a master, Yeats managed to remain forever the contemporary, to such a degree that it becomes hard for us to judge just how much of our minds he invented. Hence our strangely ambiguous response to his quotability. Some “resisting” readers might prefer if they felt less indebted.