Rare and authentic Magna Carta discovered long after it was purchased for $27.50

A "copy" of the famous document known as a symbol against tyranny and as a "cornerstone of freedom" has been discovered to be authentic.

Harvard Law School in 1946 bought a "copy" of the Magna Carta for just $27.50 from a London legal book dealer, Sweet & Maxwell, according to a news release.

One professor, David Carpenter, noticed the digital version of the document on the Harvard Law School Library website and realized it might be authentic.

The Magna Carta is a royal charter of rights agreed to by King John of England in 1211.

Nicholas Vincent, a professor of medieval history at the University of East Anglia, said it is "a totem of liberty, central to our sense of who we are: a freedom-loving, free-born people."

He added, "It is an icon both of the Western political tradition and of constitutional law. If you asked anybody what the most famous single document in the history of the world is, they would probably name Magna Carta."

The press release notes that "Carpenter and Vincent also observed that the first line with elongated letters and a large capital E was consistent with the six other originals of Magna Carta 1300."