Four previously undiscovered letters written by Albert Einstein have sold at auction for more than £7,000.
The Nobel Prize-winner wrote the letters, said to be a "unique collection", to socialist philosopher Corliss Lamont, who was accused by Senator Joseph McCarthy of being "un-American" for his suggestions that the US should maintain a relationship with the Soviet Union.
Lamont, who was chairman of the National Council of American-Soviet Friendship, was cited for contempt of Congress after he refused to answer questions at McCarthy's subcommittee in September 1953.
The four previously-undiscovered letters, which were found in a yard sale, were expected to sell for £3,200, sold for a total of £7,688.70, including buyer's premium, said Guernsey-based PFC Auctions.
In the first of the letters, dated January 2 1954, the scientist told Lamont he had "rendered the country an important service".
Einstein, who had settled in the US in the 1930s, said: "There is one point in your statement which I regretted. It is your declaration that you have never been a member of the Communist party. For party membership is a thing about which no citizen has any obligation to give an accounting for."
The typed letter, on embossed headed paper from 112 Mercer Street, Princeton, New Jersey, USA, is signed "A. Einstein" in black ink.
In a reply on January 25, Lamont said he was preparing a pamphlet entitled Challenge To McCarthy, and asked to include a letter from Einstein to high school teacher William Frauenglass, who was under investigation by the Senate internal security sub committee.
On January 26 1954, Einstein sent a copy of the letter, which had appeared in the New York Times in June 1953, in which he told Frauenglass: "Every intellectual who is called before one of the committees ought to refuse to testify, he must be prepared for jail and economic ruin, in short, for the sacrifice of his personal welfare in the interest of the cultural welfare of this country".