Thinking of the Matisse show at MOMA - Matisse: Radical Invention 1913-1917 - fills my head with the color blue. There are plenty of artists known for blue - Vermeer and Yves Klein, to name a couple - but there is something about Matisse's blues that makes your mouth water in a different way. Seductive, charming, often with a tinge of rosy undertone that somehow brings a little bit of peace to the soul - Matisse makes this most primary of colors speak with an elegant, eloquent voice. The color, rich and satisfying on its own merits, is also part of the story the show is telling. The dates refer to the years between the time Matisse arrives back in Paris after his momentous trip to Morocco and when he leaves for Nice, where he enters one of his most defining periods. In between is World War I, and the earthshaking consequences of the development of Cubism by his rival Picasso (and others) - two mighty forces that Matisse must contend with as he lands back in France. The grim conditions imposed by war make themselves felt; small intimate drawings of spouses of artists off in the war, created by Matisse to be sold to help refugees in France, are a sober reminder of real lives disrupted, and the skeletal shapes of Notre Dame's towers in a popular painting in MOMA's permanent collection become apocalyptic in the context of 1914 Europe. During these years Cubism challenged Matisse with its mix of intellectualized, minimalized, monochromatic rules - his striving for solutions seems obvious once explained, though I hadn't thought about it before. His choice of monochrome, in contrast to the greys and browns of Picasso and Braque, is blue, a color that allows him to keep the element of sensuality that is his trademark, while also allowing him to focus in new ways. Again, a painting from MOMA's collection is the best example: The Blue Window (1913) can in fact be seen as a Cubist-inspired work, with evident geometry in objects and a palette that, while not that of a monochrome purist, is restrained to a few yellows and reds swimming in a gorgeous sea of blue. This is a satisfying show, designed to teach, to please, and to make you think.