Peter Schjeldahl at The New Yorker:
The show eases, somewhat, the famous difficulty of telling a Picasso from a Braque in the woodshedding period of 1909-12, which is termed Analytic Cubism. A wall text—a welcome one among far too many that are prolix, making for an installation that is like a walk-through textbook—points out Braque’s tendency toward ruddy luminosity and Picasso’s toward dramatic shadow. Still, the works speak a single visual language of clustered forms that advance and recede in bumps and hollows, with shaded planes, often bodiless contours, and stuttering fragments of representation. It’s said that they rendered objects from different viewpoints simultaneously, but seeing the works that way is beyond me. You don’t take in an Analytic Cubist picture as a whole. Rather, you survey it, as with an aerial view of some terrain that you must then explore on foot.
Oddly, for a style that crowds the picture plane, spatial illusion is crucial to Cubism. You know that you’re on the right track when, to your eye, the “little cube” elements start to pop in and out, as if in low relief. There’s a vicarious tactility to the experience. What the elements represent matters far less than where they are, relative to one another. To see how this works, it helps to take note of an endemic formal problem of Cubist painting: what to do in the corners, where the third dimension can’t be sustained.
more here.