If Old Masters sculpture is just something you walk past on the way to see Old Masters paintings, the National Gallery's "Tilman Riemenschneider, Master Sculptor of the Late Middle Ages" could change that.

A surprisingly gripping little show, it offers not only an incisive look at the work of one of the greatest woodcarvers who ever lived, but also insight into the sculpturemaking enterprise practiced by Northern European masters before the Renaissance. It was a time when churches were the chief patrons of art, gigantic altarpieces and church facades were being commissioned, and sculptors had to master their craft before they were allowed to make art. (What a concept!)

Looking at 50 Riemenschneiders is a rare opportunity: There hasn't been such a show anywhere for 70 years, and there won't likely be another soon. People cross oceans to see his amazing carvings of saints, sinners and biblical scenes now scattered to the winds--though all were created for late 15th- and early 16th-century churches, private chapels and civic buildings in and around the Bavarian town of Wuerzburg. He and 40 assistants were chiseling away on these works--not only in wood but also in marble, alabaster and limestone--as Columbus set sail for America.

What makes them amazing isn't just the virtuoso carving, the individualized faces and veined hands of bishops and apostles. It's the empathy and humanity that Riemenschneider projects into these scenes: the animated young Mary handing her infant son over to her mother, Saint Anne, and the delight the child exhibits as he heads into her lap, his arms outstretched and his leg awkwardly stiffened, as if he were trying to take a first step.

You see it also in the many animals that accompany his saints. You know the artist loved them: Saint George's dragon, far from fearsome, seems to have rolled over to get his belly scratched, and the lion whose slivered paw Saint Jerome so tenderly tends is docile as a pussycat.

Riemenschneider may be anchored to the late Gothic international style (or so his scholars say) by the use of elegant, slightly elongated forms and by compositions lifted from engravings by Martin Schongauer, but his subjects, biblical or not, seem wholly of this world. Which, at least in spirit, aligns him with early Renaissance humanism. True, these are mostly religious works: saints, annunciations, lamentations and such. But they teach by empathy, not edict. And you don't have to be a churchgoer to love them.

Some of the most engrossing scenes seem almost secular if you don't know the text. Consider one of the two fabulous relief panels from the altar of the parish church of Mary Magdalene in Munnerstadt, which Riemenschneider created between 1490 and 1492. Dedicated to the story of redemption as exemplified in the life of this repentant prostitute, this altar includes what is arguably the most remarkable work in the show. A relief panel titled "Christ in the House of Simon," it is one of four made for the high altar and is on loan from Munich. It depicts Mary Magdalene kneeling in the foreground before Jesus, who sits at a table with three others while being served wine.

Having washed the feet of Christ with her tears, Mary is here seen drying them with her long tresses as Simon, on the right, holds up his hand--and the corner of the tablecloth--to keep from being tainted by the proximity of this woman of ill repute. The narrative intensity is heightened by the shallow space into which the whole scene has been compressed.

Though only a few inches thick, this carved relief manages to create the illusion of a space deep enough for a large square table and six people--not to mention the cooked chicken and loaves on the table. The distinctive carving of Mary's robes--characteristic of all of Riemenschneider's drapery--is truly spectacular and recalls the Flemish paintings of Jan van Eyck and Rogier van der Weyden.

Riemenschneider also created the accompanying panel, "Noli me Tangere," the composition of which was adapted from the engravings of Schongauer. The carved figures of the four evangelists here were also originally installed in the predella beneath Riemenschneider's altarpiece but now reside in Berlin.

This Munnerstadt altar was apparently the first of many that Riemenschneider delivered uncolored (at the time, such works were customarily painted in polychrome and metal foil). It was later painted and gilded, only to lose its color again in the 17th century, when the entire altarpiece was dismantled and its elements dispersed.

Only a few of the sculptures here still have their paint. But those without it speak far more eloquently to modern eyes.

A word on Riemenschneider's technique appears early in this show, making the work seem even more remarkable. To make a standing figure, we are told, a tree trunk (preferably of linden, or "limewood") was halved and then clamped horizontally to a rotisserie-like workbench, where it could be rotated while the sculptor (or assistants) roughed out the form using axes, chisels, adzes and mallets. We are reminded that the wood had to be masterfully cut so as to minimize cracking with future changes in heat and humidity. Surface patterns, for instance of cloth, were sometimes created through the use of punches.

If you begin to wonder how the protruding, lavishly folded drapery and hands could be cut this way, it is explained that some parts of the figure were carved separately and later attached with dowels, which can be seen in some of these works. They only become more marvelous once one knows how they were made, and more remarkable for what seems, overall, to be their remarkably good condition. There was also the problem of insects: One fabulous carving of Saint Anne is covered with perforations, but such damage is surprisingly rare. Other works were lost to fires or to the later secularization of the church.

Here, as we peruse these beautifully installed works, we take them for granted. But many of these altarpieces and other sculptural ensembles were separated long ago and now reside in different museums. A touching little limewood Nativity, for instance, comes half from Berlin and half from Aschaffenburg. Some of the curators who served as couriers for these treasures from abroad had never seen them all together. Nor had the visitors to their respective museums.

The National Gallery's installations are always fine. But this one is exceptional in that it offers close-up scrutiny of works that, even when intact, were often too far away to see easily. As we walk up to the Munnerstadt carvings, for instance, we shouldn't forget that they were originally on a high altar. And that the carvings on the wings, the doors of the altar, were often out of view except on Sundays and certain religious holidays.

Here we can walk around these works and examine them from different vantages, and for most of them there isn't even a vitrine to keep us from observing at close range the warm, sensuous color of the limewood, Riemenschneider's favorite medium. And seeing how the backs have been hollowed out to prevent cracking, or how wood pegs have been used to attach hands and areas of deep-cut drapery.

We are also reminded of Riemenschneider's genius at exploiting the various points of view from which his works would be seen, controlling light and shadow to heighten dramatic effect. Which brings us to one of the curiosities that hang at the end of this show: "Madonna and Child on the Crescent Moon," a two-sided piece made to be suspended high up in the vault of the church of Saint Barbara in Wuerzburg. The other is the charming and curious "Little Chandelier Woman," one of the very few surviving civic commissions. Mounted on a chandelier made of antlers, she originally hung--apparently without the antlers--in the town hall in Ochsenfurt am Main.

Surprisingly, Riemenschneider is well represented in American collections: Both Dumbarton Oaks and the National Gallery own single works. The National Gallery's "Bishop Saint," made from two blocks of limewood, was at some point cut down from a full-length to a half-length figure and turned into a reliquary. This we know from the diamond-shaped cut in the saint's chest, where a large jewel was once installed. This cut is now discreetly covered with a small wooden patch so as not to detract from the face.

Though not a particularly interesting work, "Bishop Saint" serves to remind us what a miracle it is that so many of Riemenschneider's wood carvings have survived at all--let alone in good condition, for which we have an army of conservators to thank.