The Children Act by Ian McEwan Jonathan Cape, 2014, 213 pages, $30   This novel is, I think, a small masterpiece, and in what follows I want to illumine how its quality arises out of a meticulous naturalism in the writing, one that gathers into the story its extraordinary mythic charge and the exquisite realisation of its central character, Fiona Maye, yet leaves us with a sense of an everyday fabric having been delineated just so, justly and so. Fiona is a respected High Court judge living with her husband, Jack, at Gray’s Inn Square in London. As the novel…