Matisse is the best painter ever at putting the viewer at the scene. He's the most realistic of all modern artists, if you admit the feel of the breeze as necessary to a landscape and the smell of oranges as essential to a still life. "The Casbah Gate" depicts the well-known gateway Bab el Aassa, which pierces the southern wall of the city near the sultan's palace. With scrubby coats of ivory, aqua, blue, and rose delicately fenced by the liveliest gray outline in art history, Matisse gets the essence of a Tangier afternoon, including the subtle presence of the bowaab, the sentry who sits and surveys those who pass through the gate. From Peter Plagens, "Bright Lights."