Breaking the Window

In 1907, Pablo Picasso unveiled Les Demoiselles d'Avignon: five women carved into jagged geometric shards, two of them wearing faces borrowed from African masks. The art world recoiled. Even Matisse, the great rule-breaker, thought Picasso was making fun of painting.

He wasn't joking. For 500 years, a painting had worked like a window onto a frozen scene. Picasso smashed the glass and started building something new in the wreckage.

Picasso and Braque threw out the oldest rule in Western painting: that you draw an object from one fixed spot. Instead they painted things from several angles at once — a face shown from the front and the side in the same instant, a guitar seen from above and below on one flat canvas.

The idea sounds chaotic, but it has a logic. When you actually look at someone, you don't freeze. You shift, you lean, you glance around. Cubism put that motion onto the canvas.