John Constable's Big Ideas

John Constable's "The Leaping Horse" is on view at the National Gallery of Art. (Royal Academy Of Arts, London)

If a single word defines "Constable's Great Landscapes: The Six-Foot Paintings," an exhibition at the National Gallery of Art that somehow manages to be both grand and tightly focused, it is ambition. And not just because the pictures at the heart of this show are so wide (six feet across, give or take).

To be sure, it was at least partly professional ambition that first moved the British painter to begin producing work on this scale. John Constable wanted his paintings to be seen, and he had figured out a secret: The bigger the canvas, the better the hanging at the Royal Academy in London, where paintings tended to be displayed from floor to ceiling. Make it large enough, and your picture would almost be guaranteed a spot at eye level. The heaviest pictures, you see, often rested on a wooden ledge that stuck out from the wall at the top of the wainscoting.

But there was also artistic ambition at work. Constable wanted detail. He wanted his audience to be able to differentiate between the light bouncing off a cloud and the light filtered through a canopy of tree branches (or dancing on the surface of a rushing brook).

You've got to go big to get that.

After an introductory gallery that includes an assortment of early, more modest-size works, "Great Landscapes" does just that, segueing to the large landscapes that, despite minor fluctuations in dimension, are collectively known as Constable's "six-footers."

Yet the artist's ambition doesn't end there. What is probably unique in the history of art is the fact that Constable also left the world a series of full-size painted sketches, or studies, made in preparation for his finished canvases. That's full-size as in six feet wide. So much for carrying around a sketchbook on visits to the countryside or a canvas you can tuck under your arm and take back to the studio. Constable went big from the get-go.

For the first time since the artist's death in 1837, eight of his finished six-footers have been reunited, side by side, with their corresponding twins.

Talk about separated at birth. If you stand back far enough and squint, it's like seeing double. Look more closely, and you'll see not just the editing process that any artist uses -- figures get painted out, a tree is repositioned on the horizon -- but that Constable worked fast and loose. There are passages in his sketches that seem to foreshadow impressionism, or even abstract expressionism. It's paint, or light, if you will, pure and simple.

Though Constable's finished paintings are certainly tighter than their corresponding sketches -- they seem to come into focus, as it were -- not all of the looseness of the preliminary studies was painted out in the final product.

Take the artist's 1825 "The Leaping Horse."

"Just what the heck is that?" asks curator Franklin Kelly, pointing to the almost Jackson Pollockian spurt of white paint splashed across a stand of trees on the left side of the finished canvas.

It is, needless to say, sunlight breaking through the branches. Still, its exuberant presence, which unapologetically reminds us that we're looking at paint, not a picture window, is precisely why it hasn't always been easy to tell the difference between Constable's sketches and his completed canvases.