A letter from Albert Einstein, which encouraged the US to develop the world's first nuclear bombs, is to go up for auction, the BBC reported.
Written to President Franklin D Roosevelt in 1939, the note warns that Nazi Germany might be able to create such weapons and suggests the US begins its own atomic program.
The letter is being sold as part of an auction of artifacts belonging to Microsoft co-founder Paul Allen, who died in 2018 at the age 65.
His personal collection will go on sale at Christie's, in New York, in September.
There will be a range of items reflecting his interest in - and influence on - computing, but the Einstein letter is expected to be the centerpiece.
It has been given an estimated value of between $4 million and $6 million. The letter, noted the BBC, was actually written by Hungarian physicist Leo Szilard with help from other scientists - but it was signed by Einstein because his status as one of the greatest scientific figures of all time made it more likely to get the president's attention.
Einstein is reported to have later regretted the letter due to its role in making America the only country - at the time - to make nuclear weapons.
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.
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.
A year later, a violin once owned by the legendary physicist sold for $516,500 at the New York-based Bonhams auction house.
In 2021, Einstein's handwritten notes for the theory of relativity fetched a record 11.6 million euros at an auction in Paris.