HAVERFORD, Pa. (AP) — Officials at a college near Philadelphia are returning a valuable letter by philosopher Rene Descartes (reh-NAY' day-CART') to its rightful owner in France.

The 17th-century missive has been in the Haverford College archives for more than 100 years. But officials there only recently realized it has illicit origins.

A researcher in the Netherlands saw the letter listed on a library inventory that the college posted online last fall.

He told Haverford it had been stolen from a French library in the mid-1800s. He also says the letter provides important insight into Descartes' thinking.

Haverford believes the alumnus who donated the letter was unaware of its provenance. Still, they are returning it to the library in Paris at a ceremony June 8.