Book excerpt: For both readers and writers of poetry, here is a concise and engaging introduction to sound, rhyme, meter, and scansion - and why they matter. "The dance, " in the case of this brief and luminous book, refers to the interwoven pleasures of sound and sense to be found in some of the most celebrated and beautiful poems in the English language, from Shakespeare to Edna St. Vincent Millay to Robert Frost. With a poet's ear and a poet's grace of expression, Mary Oliver helps us understand what makes a metrical poem work - and enables readers, as only she can, to "enter the thudding deeps and the rippling shallows of sound-pleasure and rhythm-pleasure."