The Archimedes Palimpsest, sold at auction at Christie’s for $2 million in 1998, is best known for containing some of the oldest copies of work by the great Greek mathematician who gives the manuscript its name. But there is more to the palimpsest than Archimedes’ work, including 10 pages of Hyperides, offering tantalizing and fresh insights into the critical battle of Salamis in 480 B.C., in which the Greeks defeated the Persians, and the battle of Chaeronea in 338 B.C., which spelled the beginning of the end of Greek democracy.

The palimpsest is believed to have been created by Byzantine monks in the 13th century, probably in Constantinople. As was the practice then, the durable and valuable vellum pages of several older texts were washed and scraped, to remove their writing, and then used for a medieval prayer book. The pages of the older books became the sheaths of a newer one, thus a palimpsest (which is pronounced PAL-imp-sest and is Greek for “rubbed again”).

After the Christie’s sale the manuscript was left at the museum by the private collector for conservation and study. This year imagers at Stanford University used powerful X-ray fluorescence imaging to read its final pages, which are being interpreted, transcribed and translated by a group of scholars in the United States and Europe.

The new Hyperides revelations include two previously unknown speeches, effectively increasing this renowned orator’s body of work by 20 percent, said Judson Herrman, a 36-year-old professor of classics at Allegheny College in Meadville, Pa. He is one of a handful of classicists who have written doctoral dissertations on Hyperides.

Hyperides lived from 390 or 389 B.C. until 322 B.C. and was an orator who made speeches at public meetings of the citizen assembly. A contemporary of Aristotle and Demosthenes, he wrote speeches for himself and for others and spoke at important political trials. In 322 B.C. Hyperides was executed by the Macedonians for participating in a failed rebellion.

“It’s a spotlight shining on an important moment in history,” said Mr. Herrman, currently a fellow at the National Humanities Center in Research Triangle Park, N.C. Until the new leaves were found in the palimpsest, most scholars believed only fragments of Hyperides survived beyond the Classical period. The mystery of Archimedes’ treatise on combinatorics, the Stomachion, was solved in 2003 by deciphering the palimpsest. Now W. Robert Connor, the president of the Teagle Foundation, which provides education and financial resources for education, called the discovery of new Hyperides text a “tour de force of the first order.”

A combination of high-tech imagery and old-fashioned deciphering, sometimes letter by letter, was used to resurrect the older text, revealing a slice of Athenian history in the days after its devastating defeat by Philip II, king of Macedonia and the father of Alexander the Great, Mr. Connor said. “The number of times you get a new text is very small,” Mr. Connor, a former professor of classics at Princeton said. “It’s like hearing an old violin played at a superb level.”

Cecil Wooten, a professor of classics at the University of North Carolina at Chapel Hill, who attended a Hyperides presentation by Mr. Herrman on Nov. 13, called the discovery “interesting and significant.”

“Although Hyperides is a very important fourth-century Greek orator, one of the canon of 10, we have very little of his speeches, and much of that is fragmentary,” Professor Wooten said in an e-mail message.

Michael Gargan, a professor of Classics at the University of Texas at Austin, said, “Every bit we get is important.” Mr. Gargan, a major scholar on ancient Greek law, noted that Hyperides wrote many speeches and had a leading reputation in antiquity, but only about six of his speeches survive.

“This obviously will contribute a great deal more,” he said. “I eagerly await seeing the text.”

In one recently discovered speech, Hyperides talks about the number of boats (220) — a number not previously clear— belonging to the Greek side in the Salamis battle, Mr. Judson said. In another speech, after the Battle of Chaeronea, he argues that the tragic defeat was the result of chance, not bad policy. In a political case Hyperides supports the Demosthenes policy that led to the Athenian defeat.

“For we chose the noblest policy and we believed it necessary to free the Greeks by taking on the risks ourselves, just like before,” Hyperides argues in a passage translated by Mr. Herrman and transcribed by Natalie Tchernetska of Riga, Latvia, a project scholar and specialist in Greek palimpsests, whom Mr. Herrman credits with first identifying the material.

“One must assign the start and the suggestion of every risk to those who make the motion, but the outcome of these things is to be assigned to chance,” Hyperides argues in the speech. “Diondas proposes the opposite happen: not that Demosthenes be praised for his policy but that I give a defense because of chance.”

Professor Herrman said the material also gives new information about inheritance laws in Athens and suggests a different timing for the Demosthenes case.

Historians had always believed that the trial of Demosthenes took place before the battle of Chaeronea, which Athens lost to the Macedonians, but the newly discovered speech shows that it was after the battle, Mr. Herrman said. “We had no idea of what the content of the trial was,” he said. “Now we have an Athenian view of their own defeat.”