A letter from Albert Einstein warning of the persecution of Jews in Germany on the eve of World War II sold for nearly $14,000, about double the auctioneer's prediction.
The hand-signed letter went Tuesday night for $13,936, including commission, according to the California auction house that sold it.
The auctioneer did not reveal who the buyer was.
The physicist writes of the importance of "rescuing our persecuted fellow-Jews from their calamitous peril and leading them toward a better future" in the June 10, 1939, letter.
Einstein praises New York businessman Hyman Zinn for his "splendid work" on behalf of refugees.
"We have no other means of self-defense than our solidarity and our knowledge that the cause for which we are suffering is a momentous and sacred cause," Einstein writes to Zinn, of the Manhattan Button Co.
The typewritten letter, hand-signed "A. Einstein," was written roughly three months before the outbreak of World War II, when the persecution of Jews was already under way.
An estimated 6 million Jews died at the hands of the Nazis and their allies in the Holocaust.
Einstein was born in Germany but renounced his citizenship in 1933, when Adolf Hitler became leader of Germany, and moved to the United States. He died in 1955.