No Second Troy is a poem written by William Butler Yeats. Some verses of the poem are:

What could have made her peaceful with a mind

That nobleness made simple as a fire,

With beauty like a tightened bow, a kind

That is not natural in an age like this,

Being high and solitary and most stern?

Why, what could she have done, being what she is?

Was there another Troy for her to burn?

The poem was one of many Irish pieces of literature that Miles O'Brien's mother tried to get him interested in. O'Brien had no interest in, or understanding of, the poetry or the history illustrated in it. (DS9 novelization: The Search)