Let Us Watch Richard Wilbur: A Biographical Study by Robert Bagg & Mary Bagg University of Massachusetts Press, 2017, 392 pages, US$32.95 ____________________________________________   You, whoever you are, If you want to walk with me you must step lively. —“Running”   What is an individual thing? —“An Event”   Once, sitting next to Richard Wilbur in a Colorado restaurant and waiting for our drinks to arrive, I passed him a plate of hors d’oeuvres. “Try the wild boar sausage,” I said. “It’s a specialty.” Tall, serene, and as nearly regal as an American poet could possibly appear, he cast a…