James Abbott McNeill Whistler RBA was an American artist active during the American Gilded Age and based primarily in the United Kingdom. He was averse to sentimentality and moral allusion in painting, and a leading proponent of the credo "art for art's sake". His signature for his paintings took the shape of a stylized butterfly possessing a long stinger for a tail. The symbol combined both aspects of his personality: his art is marked by a subtle delicacy, while his public persona was combative. He found a parallel between painting and music, and entitled many of his paintings "arrangements", "harmonies", and "nocturnes", emphasizing the primacy of tonal harmony. His most famous painting, Arrangement in Grey and Black No. 1, commonly known as Whistler's Mother, is a revered and often parodied portrait of motherhood. Whistler influenced the art world and the broader culture of his time with his theories and his friendships with other leading artists and writers.