A poem with two numbers

My friend Carol Ann Heckman has studied with Denise Levertov and feeds voraciously on her work.  For many years I have loved Levertov's "The Secret" and today, rereading an email from Carol Ann, I went looking for a mathy poem by this beloved poet.  I found the following -- with two numbers (and a hint of recursion):

     The Mockingbird of Mockingbirds     by Denise Levertov

     A greyish bird
     the size perhaps of two plump sparrows,
     fallen in some field,
     soon flattened, a dry
     mess of feathers--
     and no one knows
     this was a prince among his kind,
     virtuoso of virtuosos,
     lord of a thousand songs,
     debonair, elaborate in invention, fantasist,
     rival of nightingales.

This poem rests on my bookshelf in Levertov's collection, Breathing the Water (New Directions, 1987).