- After 1910 there began in Vienna a movement which regarded Mach's positivist philosophy of science as having great importance for general intellectual life [...] An attempt was made by a group of young men to retain the most essential points of Mach's positivism, especially his stand against the misuse of metaphysics in science. [...] To this group belonged the mathematician H. Hahn, the political economist Otto Neurath, and the author of this book [i.e. Frank], at the time an instructor in theoretical physics in Vienna. [...] We tried to supplement Mach's ideas by those of the French philosophy of science of Henri Poincaré and Pierre Duhem, and also to connect them with the investigations in logic of such authors as Couturat, Schröder, Hilbert, etc.
- Thomas Uebel, "On the Austrian Roots of Logical Empiricism" in Logical Empiricism — Historical and contemporary Perspectives, ed. Paolo Parrini, Wesley C. Salmon, Merrilee H. Salmon, Pittsburgh : University of Pittsburgh Press, 2003, p.70. ; About the Vienna Circle