Answer: the same one Dr Johnson gave when a lady asked him how he had come to give a totally wrong definition of the word "pastern" in his tremendous Dictionary of the English Language.
Ignorance, Madam, pure ignorance.It's never too late to make amends, though. Here is me on Bill:
I nurse the private notion (it hardly rises to the level of a theory) that while bohemian rules-don't-apply-to-me egotists of the type drawn so memorably by Paul Johnson in his book Intellectuals — Shelley, Hemingway, and so on — have certainly given us much, the truly towering geniuses are solid citizens, morally centered, and, with due allowance for the minor foibles of genius, fundamentally bourgeois.
Yeats conforms to this notion. He was a filial son, a loyal sibling, a reliable friend, a brave and conscientious patriot, and a loving father. He was essentially uxorious, too, his few mild lapses in this respect being in line with his aristocratic/romantic ideals, ideals his wife understood and tolerated. He was kind and forbearing towards his admirers. For example, he came to detest "The Lake Isle of Innisfree," written in 1888, through having had to read it so many times to audiences; yet he went on gamely giving it to them until nearly the end of his life, because he knew how much they loved it. (And still do. When, in 1997, the London serious-music radio station Classic FM polled their listeners to nominate their favorite poems, "Innisfree" ranked No. 17, ahead of Shakespeare's Sonnet Eighteen, "Ode to a Nightingale," and "Kubla Khan." "The Cloths of Heaven" and "When You are Old" also made it into Classic FM's top 100.) A good man, an admirable man, for all the silliness. And yes, yes! — William Butler Yeats was it.