“Unfinished” is a grand sweep, showing works from the Renaissance up to today. The third floor shows unfinished works by masters like van Eyck, Michelangelo, Leonardo Da Vinci, Titian, Rubens, Rembrandt, Velazquez, van Eyck, Turner, Mezel, and Sargent, and so forth—more than enough to make one gasp, amazed by the concentration of genius creations to be absorbed.