Picasso co-invented an art style in response to a single Cézanne painting

Pablo Picasso and Georges Braque developed Cubism between 1907 and 1914, but the catalyst was Picasso's encounter with Paul Cézanne's work — particularly Cézanne's tendency to show objects from multiple viewpoints simultaneously. Cubism took this to its logical extreme: a face shown in both profile and full frontal at once, a guitar fragmented into geometric planes. When Henri Matisse first saw Picasso's proto-Cubist 'Les Demoiselles d'Avignon' in 1907, he thought it was a hoax. Within a decade, Cubism had reshaped not just painting but architecture, literature, and fashion design.

Source: Richardson, A Life of Picasso, Vol. 2 (1996)