 In his review (Reichenbach, 1935e) of Popper’s The Logic of Scientific Discovery, Reichenbach suggests that theories are ordered by their prior probability, and the theory with the highest prior is further tested. In Experience and Prediction (1938c) and in his reply to Nagel (Reichenbach, 1938a), published in the same year, Reichenbach first formulates the distinction between the context of discovery and the context of justification with regard to mathematics: the mathematical relations are what they are, and how we come to recognize them is an entirely different, psychological matter: