The context of the letter indicates that it is in reference to Neiman's work, "There is a Tyrant in Every Country."
Neiman's address listed as:
Anderson Creek
Big Sur, California
Letterhead reads:
Harcourt, Brace and Company, Inc.
Publishers
383 Madison Avenue
New York 17, NY
Personal names mentioned in the letter:
Henry Miller
William Saroyan
Mr. Leite
Elizabeth Ann McMurray