The end of World War II marked the beginning of a period of prosperity in the United States, but mankind's potential for brutality, displayed during the Depression and wars of the first half of the 20th century, cast a shadow over accepted notions of progress.

A critique of established political, philosophical and religious institutions arose, coupled with shrinking support for the once prevalent belief that technology and science would make the world better.

Among artists, this resulted in a turning away from 1930s Social Realist scenes, and Impressionist infatuation with subject matter drawn from the societal change accompanying the Industrial Revolution, to attempts to uncover the nature of man in a post-atomic era by probing the subconscious and personal.

The artists of "Modern Masters: Midcentury Abstraction From the Smithsonian American Art Museum," at Westmoreland Museum of American Art, were at the top of their form in the 1950s. Their abandonment of representation, new approaches to composition, and bold, undisguised brush strokes shocked, but also succeeded in jockeying New York to the position of world art capital.

The exhibition comprises 37 paintings and six sculptures, many of them exceptional, and, with so many large works, dominates the museum's changing exhibition galleries. It leads with important Abstract Expressionists Robert Motherwell, Franz Kline, Hans Hofmann and Adolph Gottlieb, their painting styles ranging from Kline's spare, almost calligraphic strokes to Hofmann's rich pastiche of paint and color.

While significant figures like Jackson Pollock, Mark Rothko and Willem de Kooning are absent, the exhibition gives opportunity to see artists often missing in blockbuster shows.

Women stand out among these, including Joan Mitchell's "My Landscape" of 1967 (compare the vigor to Pollock), Helen Frankenthaler's "Desert Pass" of 1976 (compare to male Color Field painters like Morris Louis) and Grace Hartigan's "Modern Cycle" of 1967.

Also exhibited are African American artists David Driskell, with his mixed media 1974 "Dancing Angel," and Romare Bearden represented by two of the collages for which he is so well known, "Mother and Child" of 1971 and "Family" of 1986.

The large color blocks of Esteban Vicente's "Spring" recall Rothko, though they appear to be on the brink of floating away from the restraints of the plane they occupy rather than illuminating a contemplative space. The figure of "Nineteen Twenty-Nine," by another lesser-known artist, Nathan Oliveira, is reminiscent of Francis Bacon in the way it is both infatuating and fearsome.

If Abstract Expressionism was a response to a world out of balance, Minimalism was a response to Ab Ex, replacing self-expression with intellectual analysis, reducing paint and canvas to bare essentials, as in seminal figure Ad Reinhardt's "Abstract Painting No. 4" of 1961. Reinhardt has put the focus on the paint lying on the surface, painstakingly hiding brushstroke, presenting nuance for discovery: appearing at first to be all-black, it actually has barely discernible variance in shape and color.

Paintings atypical of what they're known for offer a welcome glimpse into Reinhardt's (1940) and Hofmann's (1938) earlier expression. Similarly, Philip Guston's "Painter III," of 1960, a barely visible chair surrounded by blocks of color, precedes the cartoon-like imagery he's remembered for.

Paintings such as Larry Rivers' "The Athlete's Dream" (1956) and Jim Dine's 1960 "The Valiant Red Car," homages to the former's family circle and to an incident in the life of the latter, are montages of recognizable imagery to which the viewer may attach his or her own story before reading those of the artists.

The few sculptures also run the formal gamut, from Ibram Lassaw's organic 1961 bronze "Banquet," a cheerily busy piece that appears capable of growth, to Anne Truitt's 1962 "Keep," a minimalized tower-like structure that plays upon notions of possession and protection.

Louise Nevelson's elegant sculptures, combinations of shapes unified by a coat of black paint, are wall mounted and deliver a surprise. "Sky Totem," of 1956, is of wood, a material she used frequently and deftly in much larger free-standing works; but "Gate V," from the "Garden Gate" series (1959-1960), which appears as wood, is cast bronze. Expectation can influence perception, and one is prompted to reconsider the works in relation to the heft the metal adds.

When viewing an exhibition of historic art, one of the more difficult things to remember is that, though part of today's visual vocabulary, it was often groundbreaking in its time. It's a gift to see these works, challenging when created, continuing as a vital part of our art heritage.