Parisians relax on an island in the Seine on a Sunday afternoon: a couple with a monkey on a leash, a woman fishing, children, soldiers, a man playing a horn. Seurat spent two years on it, making dozens of studies.

It is made of tiny dots of pure color, a technique later called pointillism. Up close you see only dots; step back and they blend in your eye. Seurat later added a painted border of dots around the edge.