Albert Einstein's handwritten notes for the theory of relativity on Tuesday fetched a record 11.6 million euros ($13 million) at an auction in Paris, AFP reports.
The manuscript had been valued at around a quarter of the final sum, which is by far the highest ever paid for anything written by the genius scientist.
It contains preparatory work for the physicist's signature achievement, the theory of general relativity, which he published in 1915.
Calling the notes "without a doubt the most valuable Einstein manuscript ever to come to auction", Christie's -- which handled the sale on behalf of the Aguttes auction house -- had estimated prior to the auction that it would fetch two to three million euros.
Bids on Tuesday opened at 1.5 million euros and quickly went past the auctioneers' estimate.
After a few minutes two bidders were left, battling it out over the telephone in increments of 200,000 euros.
The 54-page document was handwritten in 1913 and 1914 in Zurich, Switzerland, by Einstein and his colleague and confidant, Swiss engineer Michele Besso.
It discusses his theory of general relativity, building on his theory of special relativity from 1905 that was encapsulated in the famous equation E=mc2, according to AFP.
Letters and other items associated with the famed Jewish scientist have been auctioned in recent years.
In June of 2017, Winners sold letters written by Einstein about God, Israel and physics for nearly $210,000, with the highest bid going to a missive about God's creation of the world.
Last year, a violin once owned by the legendary physicist sold for $516,500 at the New York-based Bonhams auction house.
In June of 2018, a letter co-written by Einstein and his wife on the day he renounced his German citizenship, after realizing he could not return due to the rise of the Nazis, was sold at an auction in Los Angeles.
In December that year, a handwritten letter by Einstein on religion, his Jewish identity and his search for meaning in life was sold at an auction for nearly $3 million.
In 2019, a handwritten letter by Einstein expressing fictitious support for anti-Semitic policies enacted by Austria went on the auction block.