A handwritten letter written by Albert Einstein warning of the dangers of growing nationalism and anti-Semitism years before the Nazis rose to power has been sold for nearly $40,000.

The Kedem Auction House says the previously unknown letter, brought forward by an anonymous collector, fetched $39,360 in bidding in Jerusalem on Tuesday night.

Einstein wrote the letter to his sister after going into hiding in 1922 following the assassination of Germany�s Jewish foreign minister by right-wing extremists. Police had warned the Jewish scientist that his life could be in danger too.

�Here are brewing economically and politically dark times, so I�m happy to be able to get away from everything,� he wrote.

Kedem says the letter was sold at roughly double its expected price.

(AP)