Norman Lear, Internet entrepreneur pay $8 million for rare copy of U.S. Declaration of Independence

One of 25

The document, in near mint condition, is one of 25 known, surviving copies of the official first printing of the declaration adopted by the Continental Congress in Philadelphia on July 4, 1776.

"It is the cornerstone document in the history of world freedom. It's as close as you can get to the founding of our country," Sotheby's Vice Chairman David Redden said in an interview with CNN.

The document is one of only four copies in private hands, and the other three have been promised to public institutions.

Twenty-one existing copies already belong to universities, historical societies, public libraries, and city halls.

The National Archives has a copy, along with the original handwritten parchment version that is on display in Washington, D.C.

"This was how Congress voted to disseminate the news of independence. So it was printed up from Thomas Jefferson's draft of the declaration and then sent around by couriers to the armies in the field, to the newly independent colonies, to the committees of public safety and surely to the British, too," Redden said.

From flea market to world record

The document sold on Thursday wasn't discovered until 1989, when a Philadelphia man bought a $4 picture at a flea market.

He found the document in between the painting and the back of the frame and took it to Sotheby's, which originally auctioned it in 1991 for $2.4 million -- the previous record for an American historical document.

"I think this is a living document. The words in this document are the words that knocked down the Berlin Wall," said then-buyer Donald Scheer.

"It is unlikely there will be another one for sale," Redden said.

Scheer was Thursday's seller.

The bidding on www.sothebys.com. began at 9 a.m. Thursday with an opening bid of $4 million. The last bid before deadline, for $5.1 million, came at 4:59:08 p.m.

Under Sotheby's online auction rules, when a bid comes in within the last five minutes of the sale deadline, the auction clock automatically extends for 10 minutes. The process repeats until no more bids are offered.

The highest known price paid for any historical document is $30.8 million for Leonardo Da Vinci's "Codex," bought by Microsoft co-founder Bill Gates at a Christie's auction in 1994.

CNN Producer Phil Hirschkorn contributed to this report.