 In 1921, 100 years after Helmholtz was born, Paul Hertz and Moritz Schlick brought out an edition of Helmholtz’s epistemological writings: Schriften zur Erkenntnistheorie. This edition made available “On the Origin and Significance of the Axioms of Geometry,” “On the Facts Underlying Geometry,” “Numbering and Measuring from an Epistemological Viewpoint,” and “The Facts in Perception.” Schlick’s part in the selection of work having to do with geometry and empirical measurement is significant. Schlick, a close associate of Einstein’s, saw the relevance Helmholtz’s work had for Einstein’s theory. For a discussion of the influence of Helmholtz on the early career of Einstein, see Cahan 2000, 70ff. 