CAMBRIDGE -- Like pale jewels glinting in the light, the first works you see when you step into ''American Watercolors and Pastels, 1875-1950" are Edward Hopper watercolors: ''Highland Light" (1930), ''Cold Storage Plant" (1933), and ''Jenness House, Truro" (1934).
The intimate and sparkling exhibition, up at the Fogg Art Museum, highlights Harvard University's rich collection of watercolors and pastels, from Winslow Homer to Willem de Kooning, with a few loans to flesh out the show. From the brilliant, careful, opaque works of John La Farge to the looser, joyful pieces by John Singer Sargent, the show celebrates the luminosity of watercolor and the many ways artists have used that medium and pastel to experiment.
Well into the 19th century, watercolors and pastels were tools for preparatory studies. Winslow Homer and James Abbott McNeill
The exhibition, organized by Theodore E. Stebbins Jr. and Virginia Anderson, tells the story of how the collection was built, with daring and luck, and charts the role of watercolor and pastel in the rise of modernism.
Hopper pushed at the edges of his realism with compositions that threw planes and angles into high relief. Look at ''Cold Storage Plant," in which he cuts off the side and bottom of a beachfront factory, bringing us up against walls and corners, which fit into a larger abstract design that includes the horizon line. This artist painted in oils in the winter and watercolors in the warm weather, and you can feel the summer sun and the soft, salty breezes of the shoreline in these works. They replace the mournful isolation so prevalent in Hopper's oils with a lighter mood.
The Fogg's second director, Edward W. Forbes, and his deputy director, Paul J. Sachs, bought the Hoppers virtually right off the easel. By Hopper's time, they'd gotten into the habit of buying works on paper by living artists, including many nascent modernists, such as John Marin.
Two splendid pieces by Marin come from a 1926 series of watercolors depicting Mt. Chocorua in the White Mountains. ''Mt. Chocorua No. 5" is more sedate and realist, while ''Mt. Chocorua No. 1" is both choppy and fluid, the scene of valley rising to mountain peak fracturing into bristling geometric forms, as if the landscape has just broken open.
As they were snapping up contemporary pieces by such youngsters as Hopper and Marin, Forbes and Sachs continued to bolster their holdings by earlier artists. Homer takes up nearly two captivating walls of the show, boldly experimenting with technique, storytelling, and composition.
The 1880 ''Sailboat and Fourth of July Fireworks," painted during the summer when he mastered the medium, on Ten Pound Island off the coast of Gloucester, is a magnificent, Turneresque piece. Homer painted it wet-on-wet, with loose washes of inky blue-black floating over explosions of bright fireworks in the distance. His ''Hunter in the Adirondacks" (1892) contrasts the vitality of the young hunter, who carries a slain woodchuck, with the mortality of the fallen tree he rests his foot upon. In this work, Homer subtly scratched arcs into the surface to create a sense of swaying branches.
Forbes and Sachs did not pursue Sargent's watercolors, but several came through gifts and bequests. ''Group in the Simplon" (1911) shows Sargent's sister, Rose-Marie Osmond, and their friend, Dorothy Barnard, in the Simplon Valley between Switzerland and Italy. The piece's asymmetry draws us in; Sargent appears to have painted quickly, but expertly, with loose strokes and delicate tones contrasting light and shadow on the women's skirts to create volume.
La Farge, well known for his stained-glass windows, was seemingly more fastidious, applying his pigment in opaque layers. His ''Chinese Pi-tong" (1879) depicts a vessel traditionally used for paintbrushes holding drooping flowers. The delicacy of the hunting scene on the wooden container pops vibrantly out, in contrast to the romantic moodiness of the dying blossoms.
Whistler drew sparingly with pastels on brown paper, letting the paper's ground take an ethereal weight as sky or water. ''The Storm -- Sunset" (1880) looks over an expanse of water toward Venice's Grand Canal and the Doge's Palace. Much of it is unmarked paper, with brilliant pink and yellow sunset tones rioting along the horizon.
The exhibition wraps up with fun, surprising work by midcentury abstract artists. Ad Reinhardt's colorful ''No. 11 (Flowers)" is shockingly unlike Reinhardt, who is best known for his black paintings. This predates those and follows his earlier geometric abstractions. Here, jazzy gem-toned passages of watercolor dance with dashes of black ink, all of which peek out through cloudy passages of milky white.
Mark Rothko's untitled watercolor (1944-46) also dates from an in-between period. He was leaving surrealism behind for the great washes of color we know him for. Those are here, in three gray bands in the background, but over these dance frenetic calligraphic forms, drawn largely in red ink.
De Kooning's fierce, voluptuous ''Reclining Woman" (1948-49) is not a watercolor, but an oil wash on paper, so it falls a bit out of bounds, but it's a dashing, intense piece that presages the artist's angry ''Woman" paintings series of the 1950s.
Watercolor and pastel came of age in the late 19th century, and their portability and low cost encouraged artists to take risks. They were -- and are -- mediums for play. Their brio shines here as brightly as their tones.