James McNeill Whistler painted his mother on impulse, when she came to London to escape the American Civil War, forcing him to evict his mistress from his house. It is hard to imagine a greater contrast than that between Whistler's outrageously flamboyant life in London--where he famously befriended Oscar Wilde and Dante Gabriel Rossetti--and the subdued, touchingly melancholic depiction of his Puritan mother he entitled "Arrangement in Grey and Black."...