Dear WO'N: I read that poem very carefully, several times, and could not understand it at all. I should be very much surprised if any of the other board members can. Fortunately I found a site with some background information that helps, but not as much as I could wish.

As a writer Yeats made his debut in 1885, when he published his first poems in
The Dublin University Review. In 1887 the family returned to Bedford Park,
and Yeats devoted himself to writing. He visited Mme Blavatsky, the famous
occultist, and joined the Esoteric Section of the Theosophical Society, but was
later asked to resign. In 1889 Yeats met his great love, Maud Gonne
(1866-1953), an an actress and Irish revolutionary who became a major
landmark in the poets life and imagination. However, she married in 1903
Major John MacBride, and this episode inspired Yeats's poem 'No Second
Troy'. "Why, what could she have done being what she is? / Was there another Troy for
her to burn." MacBride was later executed by the British.