PLANCK, Max (1858-1947). Four autograph letters, one autograph postcard and one typed letter signed (‘M. Planck’, and in one instance ‘Planck’) to Moritz Schlick, Heidelberg, Berlin-Grünewald, Leipzig and Gmund am Tegernsee, 23 November 1919 – 21 August 1927, together 13 ½ pages, various sizes, in autograph and one page, large 4to, typescript, one envelope.
In the earliest letter, written shortly after the death in childbirth of his daughter Emma, Planck writes to express regret at not being able to come to Rostock (where he was to have been awarded an honorary doctorate jointly with Einstein), regret which he admits is overshadowed by the deeper pain of his loss of his daughter, ‘the only one left to me, for her twin sister was taken from us 2½ years ago, also in childbirth … So of the four children of my first marriage only one son, the youngest, is left’. In a letter of June 1921, Planck offers encouragement on the advancement of Schlick’s career, referring to the possibility of a post in Kiel. In September of the following year, in a letter written jointly with the secretary of a conference, Planck congratulates Schlick on a paper he had presented on the philosophical problems raised by the theory of relativity, stressing the importance of the philosophical grounding of the natural sciences. In November 1925 and again in June 1926, Planck writes, after consultation with Einstein and Max von Laue, about the possibility of finding a position either in Berlin or in Vienna for the logical empiricist (later founder of the ‘Berlin Circle’) Hans Reichenbach. The last letter, written in August 1927, offers a long philosophical reflection in reaction to Schlick’s essay Vom Sinn des Lebens (On the purpose of life).
Moritz Schlick (1882-1936), a founding further of logical positivism and the central figure in the Vienna Circle, became closely associated with the philosophy of science from the mid-1910s, distinguishing himself in particular with a paper in 1915 on Einstein’s special theory of relativity. The Moritz Schlick Nachlass, including copies of his correspondence, forms part of the Vienna Circle Archive at the Noord-Hollands Archief in Haarlem.