Sketch for View from Mount Holyoke, Northampton, Massachusetts, after a Thunderstorm (The Oxbow) by Thomas Cole

This is Thomas Cole's compositional sketch for his most famous painting, "View from Mount Holyoke, Northampton, Massachusetts, after a Thunderstorm", better known as "The Oxbow." Painted in 1836 in oil and pencil on a small composition board, it is a window into the mind of the artist who founded the Hudson River School. The finished six-foot canvas hangs at the Metropolitan Museum of Art. This sketch shows him thinking through an idea that was enormous for a young nation: where does wild America end and cultivated America begin?

Look at the painting in halves. A dark thunderstorm pours rain over the left side of the valley, above untamed forest. On the right, the clouds break open and sunlight falls on orderly fields and tiny settlements along the snake-like bend of the Connecticut River. The sketch makes the argument bluntly visible, two weather systems, two futures, one canvas. Cole painted the boundary between them as a crackling seam of light.

The view is real. Cole climbed Mount Holyoke in western Massachusetts to find it. The oxbow in the river is a known landmark. But the split-screen sky is his Romantic invention, a visual essay on the debates of his time. He grew up in industrial England and watched factory smoke choke the landscape. In America, he saw a second Eden, and was already watching it disappear under the plow. In the finished painting, he inserted a tiny self-portrait: a painter at an easel, looking back at you from the valley floor.

This sketch is not a masterpiece. It is a workbench. And you can see, in its raw contrasts and unblended edges, an artist drawing a line through his own country.