Capturing a moment in time—when sunset pinkens haystacks, or mist rolls across Westminster Bridge—was to become a Monet trademark. His public image, groomed by both the artist and admiring critics after he became famous in Paris in the 1860s, was that of the painter of the plein air, who dragged his canvases to open fields and empty beaches in order to capture immediate impressions. But as this new show reveals, that image was carefully cultivated. Keen to present himself as an artist who reacted to nature in the moment, Monet always styled himself as a sort of “anti-draftsman,” say the show’s curators, James A. Ganz and Richard Kendall. To the press, he denied the importance of drawing as part of the creative process. “In those famous shots of him at Giverny, he’s always holding a cigarette … never a pencil,” notes Ganz. “It was lying by omission. He didn’t want to complicate the story of how he created his paintings.”

Happily, “The Unknown Monet” does. Gathering, for the first time, his drawings in pencil, chalk and pastels, it shows that Monet was an accomplished graphic artist, whose early obsession with line and faithful representation informed his later departures from them. In truth, he drew throughout his life, stuffing sketchbooks into his pockets on long tramps through the French countryside and coast. The exhibit charts Monet’s start as an obsessive childhood drawer, keen to try contemporary styles ranging from “scribbling” to wispy evocations of atmosphere with chalk and shade. An 1857 pencil drawing of an alley of trees, done when Monet was 17, shows a sophisticated use of shading and suggestion, and his early sketches of harbor scenes fuse precision and atmosphere.

He used sketches not as actual plans for paintings, but as ways of thinking about subjects he’d elaborate on in oils. His sketchbooks—formerly seen only by hard-core scholars who trekked to the archives at the Musée Marmottan Monet in Paris, but now digitized in an interactive display for the show—contain swirls of purple crayon, the initial stages of water lilies. And in his pastels of Charing Cross and Waterloo bridges—done in 1901 as a diversion while waiting for his waylaid luggage, containing paints and brushes, to arrive at the Savoy Hotel—are the seeds of his famous oils of the Thames. When the baggage showed up, the famous painter acknowledged that it was “thanks to the pastels, made swiftly, that I can proceed.”

Monet also introduced in his drawings composition techniques he would later employ as a painter. The 12 pastels of a flat green field—three of which appear in “The Unknown Monet”—are his first experiments using serial imagery over different times of day, a theme he’d revisit about a decade later with his haystack series. In “After the Rain” (1868) a pewter sky breaks into tans and pinks, followed by a somber “Twilight” and “Nightfall,” in which the field recedes under billowing violet clouds shot through with a salmon-lemon sunset. As this show makes refreshingly clear, Monet didn’t need his paints to make luminous explorations of time, light and nature.