Throughout history, works of art have been left unfinished, for a wide variety of reasons. Some of these have, over time, become as valuable--or more--as completed works by the same artist. Spanning the 15th to the 20th centuries, The Unfinished Painting looks at 50 such works by old and modern masters, including Van Eyck, Da Vinci, Michelangelo, Gilbert Stuart, Manet, C zanne, Matisse, and Mondrian, and exposes the reason for each one's abandonment,...