What is beauty? Is mathematics beautiful?

     My thoughts have been turned to the beauty of mathematics by stumbling onto a very fine article, "Beauty Bare: The Sonnet Form, Geometry and Aesthetics," by Matthew Chiasson and Janine Rogers -- published in 2009 in the Journal of Literature and Science and available online here.
      The article opens with this quote from A Mathematician's Apology (see p. 14) by G. H. Hardy:       Beauty is the first test:  there is no permanent place 
                                                   in the world for ugly mathematics.

Today I'm puzzling over what "beauty" means . . .   

The Chiasson-Rogers article then goes on to connect beauty with Euclid by quoting the opening line from a sonnet by Edna St. Vincent Millay; here is the entire text of Millay's imaginative and thoughtful stanza:

by Edna St. Vincent Millay

Millay's poem has appeared in this earlier post which includes an additional view of a mathematician in the poem "Two Sorrows" by David St. John.  For a variety of "poems starring mathematicians" -- follow this link.