In 1859, a contemporary described landscape painter Sanford Gifford as "the most poetical of our American artists, whose pictures are like poet's [sic] dreams." Almost 150 years later, that still seems to get him right: Even the very latest crop of wall texts and catalogue essays can't avoid the word "poetic" in describing Gifford's art. Today, the National Gallery of Art launches a major Gifford survey. The show makes clear that his paintings are just as poetic as everyone has always said. Depending on your point of view, that's either high praise or a sign of trouble.

From his first paintings of the early 1850s to the pictures painted just before his death in 1880, Gifford's landscapes are almost always things of striking beauty. A golden sun makes clouds glow pink on the horizon; limpid air, lit up as though transfused with light, floats through his expansive spaces. You can almost hear the plaintive solo of a Schubert clarinet soaring up through Gifford's skies. This painter's nature isn't red in tooth and claw; it's dusky rose from head to toe.

Even dedicated city slickers have probably witnessed plangent moments like this in nature. If the atmospherics are just right, they can happen on the Mall as easily as in the wilderness. It's hard to imagine anyone whose heart isn't touched by them. And it's hard to think of many other artists who managed to capture such moments as consistently as Gifford did. Walking through this show's galleries, there's hardly a picture that doesn't make you feel a thrill of serene melancholy.

Unlike some of his colleagues in the so-called Hudson River School, Gifford didn't seem to care too much about fussy details of geology and botany. His pictures aren't about information so much as about mood and sentiment. His goal isn't to do justice to the glories of nature. It's to guarantee that nature will do justice to the glorious feelings that we expect to get from her. Gifford didn't just capture the "vaporous obscurity" that some contemporary critics panned. He constructed it, over and over again.

A room toward the middle of the National Gallery show includes a few small pictures that seem to have been closely based on specific glimpses of nature in the raw -- pictures either painted out-of-doors or taking off from outdoor studies. They're colored pretty much as you'd expect: gray bark, green leaves, blue skies fading to white in the distance. That same room also contains the finished exhibition pictures Gifford built from such closely observed nature scenes. In these larger works, the original hues are almost always upstaged by veils of pinks and golds and salmons. If nature refused to dish up the poetry that Gifford and his collectors were looking for, a well-stocked box of paints could give her a helping hand.

When Gifford's landscapes were -- or are -- described as "poetic," the reference isn't simply to any form of highly structured eloquence; it doesn't mean to call to mind the trenchant verse of Alexander Pope or Philip Larkin. It seems specifically to point to the sort of high-flown, heartwarming verse that was a specialty of the Victorians. That can include the soaring words of Alfred Lord Tennyson -- not always quite coherent, but thrilling to intone. But it also includes the poems of Sir Walter Scott. And anyone who has galumphed along through the 4,000 or so lines of Scott's "Lay of the Last Minstrel" ("The way was long, the wind was cold, /The Minstrel was infirm and old . . .") will think twice before imputing "poetic" skills to a painter they admire.

Gifford's poetry, however pleasant, isn't a poetry of astute description or analysis. Like Scott's, it is essentially a poetry of escape -- and always to the same, well-known place.

Gifford's father was in the iron-foundry business, and that made his son a man of independent means, college-educated and with a gentleman's training in art. Many of the major collectors of his landscapes made bags of money in guns and trains and manufacturing. Gifford's beloved Kaaterskill gorge was opened up only when a consortium of local tanneries agreed to pay for a proper road. And yet in the 72 paintings at the National Gallery, you won't find a single smokestack or locomotive. A lone steamship, painted as the barest dot on the horizon of one nautical picture, is the only detail in this entire show that evokes the modern industry that permitted Gifford's way of life.

There are moments of unsentimental, positively un-poetic energy in Gifford. Look closely at the details in his rocks and shadows, or at the brushwork in his roughest oil sketches, and you'll find an unforgiving pro at work. But in almost every case, this toughness is drowned in a sweetly glowing light determined to draw our eyes away from it.

One unusual painting shows the Union regiment Gifford served in during the Civil War, bivouacked in a field near Frederick. A strip along its bottom includes an impressive mess of everyday details -- soldiers drying cloaks and cleaning guns; black workers boiling water and butchering meat -- but they seem entirely at odds with, rather than reinforced by, the brightly poetic skies and hilltops that fill the rest of the picture.

An important exhibition on the roots of impressionism was recently organized by the Tate in London, the Musee d'Orsay in Paris and the Art Gallery of Ontario in Toronto. Its curators argue that Turner, Whistler and Monet were willing to take the smoke and smog of European industry and use them to build new, modern ideas of beauty. Here in the United States, at that same moment, Gifford preferred to lose the modern world behind a fog of old-time poetic prettiness.

Hudson River School Visions: The Landscapes of Sanford R. Gifford is in the West Building of the National Gallery of Art, on the Mall at Sixth Street NW, through Sept. 26. The gallery is open daily 10 a.m. to 5 p.m., Sundays 11 a.m. to 6 p.m. Admission is free. Call 202-737-4215 or visit www.nga.gov.

For more of Blake Gopnik's reviews, in print and on video, please visit www.washingtonpost.com/gopnik.

More about sentiment than information: "A Gorge in the Mountains." "A Lake Twilight," one of the Sanford Gifford paintings at the National Gallery of Art.Images that evoke the high-flown, heartwarming verse of the Victorians: "Sunset Over the Palisades on the Hudson."