Mathematician and book collector Guglielmo Libri was born on 2 January 1802 in Florence. Having studied at the University of Pisa, he was appointed there as Professor of Mathematical Physics in 1823. In 1831 he moved to the Sorbonne as Professor in the Calculus of Probability. Libri was a known bibliophile.
When in 1841 the French government set up a commission to supervise the creation of a Catalogue général des manuscrits des départements, he was appointed its secretary. Between 1841 and 1846 he visited numerous libraries from which he stole items, including the Bibliothèque Royale, the Bibliothèque Mazarine in Paris, and the Archivio Mediceo in Florence. Once under suspicion, he disposed of his collection. In 1847, part of it was acquired by Bertram, 4th Earl of Ashburnham. Having been put under investigation in 1848, Libri fled to London with eighteen crates of books and manuscripts. His case came to trial in Paris in June 1850 and he was found guilty in absentia. Libri in the meantime was active again as a book dealer without impediment, and Sotheby’s held ten auctions of his material between 1849 and 1865. In 1868 he left England for Florence and settled in a villa at Fiesole where he died in September 1869. After his death Léopold Delisle proved conclusively that Libri was a criminal. In 1888 the Bibliothèque Nationale acquired the 166 items which Ashburnham had purchased. Libri may well have been the greatest book thief ever.