Claude Monet’s Impression, Sunrise marks a great leap forward in the history of painting. Looking out his window in the French port of Le Havre, Monet painted the city harbor in the early morning light. The resulting work would shake the art world and open the door for the Impressionists.

As the title suggests, in Impression, Sunrise Monet sets out to present you with an impression of the harbor at dawn. In other words, his intent is not to paint a detailed study of the harbor, with every coil of rope reproduced in agonizing detail. No, Monet has bigger ambitions. He does not want to give you a description, but rather a fleeting sensation, an impression of the sun poking through the early morning haze.

Monet pioneered a host of unconventional techniques in order to capture the “impression” of the sunrise. Perhaps the most important is his use of swift, broad strokes, which obscure the minute details that Monet sought to omit.

More broadly, instead of focusing on the physical objects in the scene, Monet concentrated on light and atmosphere. Look at the attention he gives to the fog, the shifting color of the sky, and the reflection of the sun on the water, rather than, say, the boats in the harbor.

You can think of Impression, Sunrise as the “Sgt. Pepper’s Lonely Hearts Club Band” of 1870s French painting: both works dramatically expanded the boundaries of their respective art fields and attracted hordes of imitators. Impression, Sunrise certainly had its detractors, at least initially, but its historical significance is undeniable (ironically, the term “Impressionism” was coined by a particularly hostile critic). Monet’s controversial techniques revolutionized the art world, and Impression, Sunrise remains today one of the most important works of the Impressionist period.