A handwritten letter by Albert Einstein in which he grapples with the concept of religion has smashed predictions and sold for nearly $2.9m, the BBC reports.
The so-called "God letter" was written in 1954 and was expected to fetch $1.5m (£1.2m) at auction in New York.
The Nobel Prize-winning scientist, then 74, wrote the one-and-a-half page note to German philosopher Eric Gutkind in response to one of his works.
It is seen as a key statement in the debate between science and religion.
"This remarkably candid, private letter was written a year before Einstein's death and remains the most fully articulated expression of his religious and philosophical views," a statement from Christie's says.
It fetched almost double the auction house's predicted price of between $1m-1.5m.