 Church’s mature view was that discussion of metaphysical doctrines is only worthwhile if they can be reformulated and developed using the logistic method. For example, he thought that the question of the legitimacy of the distinction between form and matter should be investigated by setting up a formal language, which is used to isolate the form of a proposition as well as of the corresponding sentence, so that one can reinterpret its non-logical vocabulary and study what is common under various reinterpretations: “this may be considered a more precise formulation of the traditional distinction between form and matter” (1956a [BE: 372–3 and 379]; 1956–72 [BE: 697]; 1959 [BE: 415, 475]).