Only rarely does an exhibition come along that presents Americans with a clear insight into the depth and range of their artistic heritage. More than enough exhibitions devoted to specific American artists or historical periods, or to in-depth studies of well-known or dimly remembered art movements, have been mounted. And several exhibitions exploring the art of particular centuries have seen the light of day.
But exhibitions devoted to the grand swing of American art as it moved from century to century or to large numbers of its all-time major works have been rare indeed.
A crucial factor has been one of quality. There simply aren't that many truly major American paintings, and neither have there been that many truly significant American artists. Those we've had have frequently been erratic. Some of our best painters produced only a handful of excellent works among many of doubtful merit, while a few of our minor artists miraculously managed to turn out one or two paintings that were truly superb.
In addition, assembling such an exhibition poses serious problems in logistics. The best American paintings are scattered throughout the United States in numerous public and private collections.
The Museum of Fine Arts, Boston, however, has surmounted all obstacles to present ''A New World: Masterpieces of American Painting, 1760-1910'' on view here. It was organized by Theodore E. Stebbins Jr., John Moors Cabot curator of American paintings at the museum, in response to a request from the Musee du Louvre to mount an exhibition of superior American paintings. Not only has he done so, he has also presented the American public with its first full view - in considerably over a decade - of American art at its best from the years preceding the American Revolution to those preceding World War I.