Boston Public Libray mural (Ceiling vault). FEW successful artists have tried to reinvent themselves in midcareer as completely as John Singer Sargent did. In 1890, at the height of his fame as a society portraitist, he accepted an offer by the architect Charles McKim to paint a series of murals for the soon-to-be-completed Boston Public Library. Here was a chance to prove that he was no artistic lightweight, but a deep thinker in the heroic tradition of Michelangelo and Raphael. Over the next 30 or so years Sargent largely abandoned his lucrative portraiture business to refashion himself as a master of monumental narratives. The resulting work, ''The Triumph of Religion,'' was a sweeping history of faith with all the tawdry grandeur and over-the-top effects of a Cecil B. DeMille film. This epic synthesis drew on sources as diverse as ancient Egyptian and Assyrian reliefs, Byzantine... (http://www.nytimes.com/2003/03/23/arts/art-architecture-sargent-s-mistake-or-maybe-not.html)