A cache of books from Thomas Jefferson‘s collection, languishing in obscurity in the rare books collection at Washington University in St. Louis, has just been discovered.

An Associated Press report explains,

Dozens of Thomas Jefferson’s books, some including handwritten notes from the nation’s third president, have been found…Now, historians are poring through the 69 newly discovered books and five others the school already knew about, and librarians are searching the collection for more volumes that may have belonged to the founding father.

The school’s collection of 74 books is the third largest Jefferson collection after the Library of Congress and the University of Virginia. The news of the discovery was announced on President’s Day.

How, you may ask, did the University library miss the fact that they had books from Thomas Jefferson’s personal library? According to the AP report:

The books were among about 3,000 that were donated to the school in 1880 after the death of Jefferson’s granddaughter, Ellen Wayles Randolph Coolidge, and her husband, Joseph Coolidge.

There was no indication at the time that any of them had belonged to Jefferson. But it turns out that 2 1/2 years after Jefferson’s 1826 death, his library of 1,600 books was sold to settle debts. Ellen Coolidge’s grandfather helped oversee her schooling when she lived at his mountaintop estate at Monticello when she was a teenager and young adult.

She was eager to acquire some of her grandfather’s books, and her husband wrote her brother-in-law, Nicholas Trist, and told him what they wanted him to buy them at the auction. They were particularly interested in books that contained Jefferson’s notes or other marks.

“My dear N. -I beg you to interest yourself in my behalf in relation to the books; remember that his library will not be sold again, and that all the memorials of T.J. for myself and children, and friends, must be secured now!-this is the last chance!” the letter reads.

Some detective work by two researchers, Ann Lucas Birle and Endrina Tay, who were researching the couple’s library, discovered that, according to the AP, “the Coolidges’ daughter and son-in-law had a relationship with one of the founders of Washington University and donated the books to the school.”

The AP report further explains:

In the hand-pressed books that were common in Jefferson’s day, printers would place the letters of the alphabet – called signatures – at the bottom of some pages so that when the books were bound, the pages would be placed in the correct order. One way Jefferson marked his books was to place a small “T” in front of one of the “I” signature, which was significant because “I” is “J” in the Latin alphabet.

“It was a little bit of detective work,” said Anne Posega, head of special collections at Washington University Libraries.

Jefferson scholars descended on St. Louis, spending three days confirming the books were genuine. They never expected to find so much of Jefferson’s library intact. Tay tells the AP, “I think the assumption was either they were with the family or dispersed.”

Significant among the finds was, “an architectural book that Jefferson consulted when he designed the University of Virginia, books with marginalia in Jefferson’s hand, and a note written in Greek on a scrap of paper, also in Jefferson’s hand.

The researchers are optimistic that there are more to be found,”We think we are going to find more treasures,” says Tay.