“Sargent and Spain,” hosted by the National Gallery of Art at Washington, D.C., through January 2, is a triumph in the genre. The show examines the influence of the artist’s seven visits to Spain on his work — the first exhibition ever so focused,  organized by the museum’s associate director of American and British paintings, Sarah Cash, with two leading authorities on John Singer Sargent, Richard Ormond and Elaine Kilmurray. This gap is surprising, given the exhortation from Sargent’s Parisian teacher, Carolus-Duran, to study “Velazquez, Velazquez, Velazquez, and at last Velazquez.”

The National Gallery has gathered roughly 140 watercolors, oils, drawings, and photographs tracking Sargent’s conversation with both the Spanish tradition — most of all with Velazquez, the greatest of the Spanish Old Masters — and the Spanish culture of his time, a source of great romance for him and his contemporaries. Particular attention is rendered to his depictions of Spanish Roma; the curators’ conspicuous sensitivity toward that people seem to be the product of deep research into their subject rather than any faddish and distracting political sensibility.

The exhibition’s first section includes the young Sargent’s studies of Spanish classics, most conspicuously Velazquez’s “Las Meninas” and “Head of Aesop.” Mr. Ormond, a great-nephew of the artist, identifies in these studies the kernel of the virtuosic command of light seen in later works like “Women at Work,” also on display, with its shimmering grapes and cobblestones and deep shadows. “To bring it off requires all his powers of concentration,” Mr. Ormond commented.

The subsequent galleries show Sargent’s studies of the people, land, and architecture of Spain, particularly emphasizing his dramatic depictions of Spanish dance and the natural settings of the provincial island of Majorca. The final section shows Sargent’s studies of Spanish popular devotional art and how they, along with all that preceded, informed his magnum opus, “The Triumph of Religion” mural series at the Boston Public Library.

The man in the street might well ask the question, deep as we are in the second century of the photographic era, what the point of painting is. “Spain and Sargent” answers by illustration; the show gathers photographs owned by Sargent, some of them most likely his own work. Through these models and reference-points for the paintings nearby, we can see Sargent laboring over the basic work of the visual and literary arts — to make something that feels truer than mere facts by the judicious emphasis or elision of detail.

For Sargent it seems there was little question of conflict between the media, and his work instead shows a productive interaction between photographic and painterly technique. Pointing to Sargent’s detailed studies of foliage — some of which reappeared in the Boston Public Library murals — Ms. Kilmurray observed that the paintings’ composition shows the “the fruit of photographic equipment, the honing in on a detail.”

It is in the handling of some photographic materials that “Sargent and Spain” provides a rare instance of interactive displays going right. The final gallery includes a large touchscreen by which visitors can leaf through one of Sargent’s digitized scrapbooks, a marvelous conclusion for a display that is so focused on the twin subjects of artistic source and artistic process.

Sargent was a master of evoking truth from the raw and rather lumpish material of reality, a citizen of the world, an innovator whose vocabulary is drawn from tradition — we dare say a perfect artist. Yet he is also a cipher; as Ms. Cash noted regarding her work, “We have very little by way of a diary, lists, letters to people.” “Sargent and Spain” draws him and his work out for us in rare fashion — making it, we dare say, a perfect exhibition.