Yesterday in Paris, Haverford College President Steve Emerson righted a centuries-old wrong, by returning a purloined letter written by philosopher Rene Descartes.

"We're not in the business of keeping stolen property," Emerson said before the trip.

As scholars and diplomats looked on, Gabriel de Broglie, chancellor of the Institut de France, received the document from Emerson, and thanked him for his "integrity and honesty," according to the New York Times.

The thank-you was expected to include a reward of 15,000 euros - about $18,000 - which, Emerson said, would help Haverford students study French language and culture.

Descartes is familiar to students far and wide, both as the 17th-century philosopher who questioned his own existence, concluding, "Cogito ergo sum" ("I think, therefore I am"), and as the father of analytical geometry whose name remains reflected in the term Cartesian coordinates.

The 1641 letter, written to a priest friend, discusses Meditations on First Philosophy, Descartes' remarkable attempt to logically derive first philosophical principles - including "I think, therefore I am."

An Italian count, Guglielmo Libri, stole many documents in the mid-19th century, including this one. The letter wound up in a collection donated to the college in 1902 by the widow of alumnus Charles Roberts. But no one at the college knew of the dubious provenance until the fall, when an inventory was posted online and a Descartes scholar in the Netherlands took notice.

"It's one of those precious finds," said the scholar, Erik-Jan Bos, who got in touch with Haverford.

Contrary to reports, the letter wasn't lost or languishing for a century.

Yesterday's ceremonies included the honoring of former Haverford student Conrad Turner, Class of 1981, who as a junior translated the document and wrote a paper about it, according to a college news release.

Calling the paper "truly a fine piece of work," Bos said, "Had the author submitted it to a major international journal, it would have been published immediately."

"We couldn't be more pleased with how this has been resolved," said Emerson, himself a 1974 Haverford grad who majored in philosophy. "In our ever-shrinking world, when strangers become friends and then partners at the click of a mouse, we want to do all we can to show, by example, what it means for scholars and citizens to collaborate for the common good."

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.

Inquirer wire services contributed to this report.