 What we ordinarily say, we say unclearly. We speak unclearly because we think unclearly. It is the task of philosophy to render our thoughts clear. … We cannot clarify our thoughts by thinking about thinking, nor by thinking about logic. We have to think about what we were thinking about. The philosopher considers a given expression, and analyses it in order to find another expression which says more clearly what the original expression said less clearly. This investigation is not linguistic. We must first know what facts are the case before we can fruitfully employ analysis for the purpose of clarifying our thoughts about the world. Accordingly, Logical Positivism fails, I think, in so far as it attempts to start from a priori assumptions with regard to the nature of language and the principles of symbolism, and, by means of these, to draw limits with regard to what we can think. Their mistake is that they seek to make everything clear at once. But it is not in this way that philosophy can develop. We must proceed step by step, beginning with propositions which we know to be true, not ruling out initially what does not fit in. (1933a: 86)