 Interestingly, Bridgman never stopped thinking about relativity. The operationalist lesson he had taken from Einstein was so dear to him that he did not shrink from criticizing Einstein himself when the latter seemed to betray his own principles in the general theory of relativity. Already in The Logic of Modern Physics he had opined: “I personally question whether the elements of Einstein’s formulation, such as curvature of space-time, are closely enough connected with immediate physical experience ever to be accepted as an ultimate in a scheme of explanation, and I very much feel the need for a formulation in more intimate physical terms” (1927, 176). Years later, when Bridgman was invited by P. A. Schilpp to contribute to the Library of Living Philosophers volume on Einstein, he issued the following “indictment” against Einstein: “he has carried into general relativity theory precisely that uncritical, pre-Einsteinian point of view which he has so convincingly shown us, in his special theory, conceals the possibility of disaster” (Bridgman 1949a, 354; reprinted in Bridgman 1955, 337). Einstein brushed aside Bridgman’s objection, merely stating that for a formal system to qualify as a physical theory it was “not necessary to demand that all of its assertions can be independently interpreted and ‘tested’ ‘operationally’” (Einstein in Schilpp 1949, 679). This exchange is reminiscent of how Einstein responded with bemused incomprehension to Heisenberg’s protest that he was following Einstein’s own lesson in treating only directly observable quantities in his matrix mechanics (Heisenberg 1971, 62–69). Bridgman also carried out further operational analysis of special relativity, and his late thoughts on the subject were published posthumously in A Sophisticate’s Primer on Relativity (1962).