For artists of the Renaissance, the key to truth and beauty lay in the past. Renaissance artists assiduously studied the sculptures and monuments of Greece and Rome and emulated them in their own work. The inspiration they found in those ancient models has echoed down the centuries, influencing the appearance of Western art and architecture to this day.

If those 15th and 16th century artists had looked more closely, however, they might have found something that would have changed their vision of ancient art and had a profound effect on their own practice. That element was color.

We now know that the unblemished white surface of Michelangelo’s “David” or Bernini’s “St. Teresa in Ecstasy” would have been considered unfinished according to classical standards. The sculpture and architecture of the ancient world was, in fact, brightly and elaborately painted. The only reason it appears white to us is that centuries of weathering have worn off most of the paint.

So entrenched has the association become between classical art and the look of white, unblemished marble, that the idea of an Athenian acropolis as colorfully painted as a circus wagon is difficult to imagine if not downright blasphemous. But now an exhibition at the Sackler Museum can help us envision what a color-drenched classical world might have looked like.

“Gods in Color: Painted Sculpture of Classical Antiquity” features full-size color reconstructions that challenge the popular notion of classical white marble sculpture, illustrating that ancient sculpture was far more colorful, complex, and exuberant than is often thought.

The reconstructions are the result of more than two decades of painstaking research by a pair of married German archaeologists, Vinzenz Brinkmann and Ulrike Koch-Brinkmann. The exhibition was organized by the Stiftung Archäologie and the Staatliche Antikensammlungen und Glyptothek of Munich, Germany, and has already been shown in a number of European cities. The Sackler is its first U.S. venue.

The Brinkmanns used various methods to detect the almost invisible traces of paint on the surfaces of the sculptures they studied. Among these was the use of raking light to reveal incised details as well as subtle patterns caused by the uneven weathering of different paints on the stone surface; ultraviolet (UV) light to bring out slight surface differences; and techniques such as X-ray fluorescence and infrared spectroscopy to analyze the types of pigments employed.

While not the first to notice the traces of color on ancient sculpture — scholars were arguing the case for painted classical sculpture as early as 1815 — the Brinkmanns are the first to bring the full armament of scientific equipment to the task.

The results are spectacular and reveal much about the way ancient Greeks and Romans viewed their world. Take, for example, the life-size figure of a Trojan archer from the temple of Aphaia on the Greek island of Aegina (excavated in 1811 and acquired by King Ludwig of Bavaria). The figure wears a shirt and leggings covered all over with an intricate red, yellow, blue, and green diamond pattern. Over this he wears a bright yellow vest inscribed with lions and griffins. A tall yellow hat with a flower pattern completes the costume.

Lest one think that all this color and pattern may have come at least partly from the Brinkmanns’ imagination, photos on the wall show how UV light revealed each of these details on the weathered and faded original.

But why is the archer so elaborately clad? According to Susanne Ebbinghaus, the George M.A. Hanfmann Curator of Ancient Art and one of the curators for “Gods in Color,” the archer probably represents Paris, who started the Trojan War by running off with Helen, the wife of King Menelaus of Sparta, and who later killed the hero Achilles by firing an arrow through his heel.

As Ebbinghaus explained, the Greeks of the classical period often represented the Trojans as Persians, whose armies they had successfully repelled in the early fifth century B.C. Persian warriors were generally shown as exotic and a bit overdressed compared with the manly and largely naked Greeks.

The contrast between Greeks and Persians can be seen in another reconstruction, that of the so-called “Alexander Sarcophagus,” discovered in Lebanon in 1887. Here the Greek warriors fight entirely naked except for a bronze helmet (apparently taking precautions against head injuries did not reflect badly on one’s valor). The Persians, on the other hand, are garbed like Venetian revelers during Carnevale. Did the Greeks actually fight in their birthday suits? Ebbinghaus was asked. “Oh, no,” she replied. “They were armed to the teeth.”

Sculptures on the pediments of large buildings have perplexed scholars who wonder how people could have made out the details of such groupings from their vantage point on the ground. The use of color helps answer that question. The Brinkmanns’ study of sculpture from the “Treasury of the Siphnians” (c. 525 B.C.) has shown that not only was color used to emphasize the details of the figures, but their names were also inscribed on the wall behind them, allowing viewers to identify both the characters and the drama in which they took part.

The Romans too painted their statuary, including the marble portrait busts whose realistic features convey such a vivid sense of the appearance and even the personalities of upper-class Romans. With the addition of color, these busts take on an illusory realism comparable to the wax figures at Madame Tussaud’s.

A particularly striking bust the Brinkmanns have pointed to is one of the Emperor Caligula (37–41 A.D.). Even taking into account the probability that the artist felt under duress to flatter his imperial subject, it is hard to equate this fresh-faced, earnest young man with the prodigy of cruelty and perversion we read about in the history books.

There is much more to see in this eye-opening exhibition, including a room devoted to the earlier art of Egypt and Mesopotamia, which shows that, by coloring their buildings and sculptures, the Greeks were merely carrying on a tradition that had begun many centuries before the flowering of their own civilization. Throughout the exhibition, the Brinkmanns’ painted reproductions are juxtaposed with original Greek and Roman art from the museum’s own collection.

The exhibition runs until Jan. 20, 2008. Gallery talks are planned in which Ebbinghaus and others will discuss the use of color in the ancient world and its rediscovery by modern scholars. Accompanying the exhibition is an activity book featuring outline drawings of the sculptures, allowing young visitors to decorate the artwork with their own choice of colors.