no owner

The poem was published as “Anonymous” because no one would own up to it.

book once owned by

Inside the cover of this book I see written the previous owner’s name, “Brett Holt.” Brett, perhaps you are dead, that would be an excuse; or you were forced by circumstance to travel light, to get rid of most of your possessions, that would be a good enough reason, otherwise I don’t know how it was you ever parted with this book.

slouches toward allusion

Yeats’ ‘slouches’: A single word, verb in this case, becomes an allusion all by itself. Certain words are owned by canonical authors.

whose words are these

They are the coin of our tongue, but words cannot be owned.