That concerning the Bertrand Russell Peace Foundation gave a list of the then sponsors, and a letter that U Thant had written for the purpose on the outside. I had talked with him about our plans among other things and written to him about them. He had been warmly sympathetic, but explained that he could not be a sponsor because of his position as Secretary-General of the United Nations. He offered, however, to write the carefully worded but encouraging letter which we printed.
Source: The Autobiography of Bertrand Russell, v.3:1944-1969 ,chap4:The Foundation,(1969)
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