German physicist who originated and developed the Quantum Theory. Awarded the Nobel Prize in 1918. ALS signed “M. Planck,” one page both sides, 6 x 8.25, personal letterhead, May 18, 1942. Letter, in German, to Gustav Krupp von Bohlen und Halbachholes, thanking him for his letter and regrets that he wasn’t able to see him. He refers to a trip to Italy and wonders if it would be possible to see Bohlen and his wife in Berlin. Torn punch holes to left side, not affecting text, several pencil notations and two stamps, and paperclip impressions to upper left corner, otherwise fine condition.COA John Reznikoff/PSA/DNA and R&R COA.