“I am a lit­tle world made cun­ning­ly of ele­ments and an angel­ic sprite,” wrote the poet John Donne in about the year 1609. He meant, of course, that he was a crea­ture of mat­ter and spir­it, body and soul. Today, we would amend his lines to read: “I am a lit­tle world made cun­ning­ly of ele­ments.” Full stop.