Why did Cubists paint faces from the front and the side at once?

Cubists painted faces from the front and the side at once because they wanted to show an object the way you actually get to know it: by moving around it. For about four centuries, European painting had followed Renaissance linear perspective, which freezes the world from one fixed eye at one instant. Cubism, pioneered in Paris by Pablo Picasso and Georges Braque in the early 20th century, broke subjects into pieces and reassembled them from several viewpoints, as if all their faces were visible at the same time.

The idea grew out of Paul Cézanne. In his still lifes, tables tilt impossibly and objects appear seen from the side and slightly from above in the same picture. Cézanne recognised that real seeing is more complex than a view from a frozen point in time. The Cubists pushed this much further. In Jean Metzinger's 1911 painting Tea Time, a woman is shown both straight on and in profile, and her teacup from the top and the side, as if the painter had walked around the table. A critic mocked it as the "Mona Lisa with a spoon"; the writer André Salmon proudly called it "the Mona Lisa of Cubism".

Braque summed up the rebellion bluntly in 1957: the hard-and-fast rules of perspective, he said, were "a ghastly mistake which it has taken four centuries to redress".