Philosophy and Wisdom

Before the time of Kant, it was generally held that whatever knowledge was a priori must be 'analytic.' ... Kant, who had been educated in the rationalist tradition, was much perturbed by Hume's scepticism, and endeavoured to find an answer to it. He perceived that not only the connection of cause and effect, but all the propositions of arithmetic and geometry, are 'synthetic,' i.e. not analytic. ... Thus he was led to the conclusion that all pure mathematics, though a priori, is synthetic; and this conclusion raised a new problem of which he endeavoured to find the solution. Bertrand Russell The Problems of Philosophy