this), and finally that she was a saint. They do not prove any of these things; but the variety of the conclusions reached shew how little our matter-of-fact historians know about other people's

Saint Joan did. If Newton's imagination had been of the same vividly dramatic kind he might have seen the ghost of Pythagoras walk into the orchard and explain why the apples were falling. Such an illusion would have invalidated neither the theory of gravitation nor Newton's general sanity. What is more, the visionary method of making the discovery would not be a whit more miraculous than the normal method. The test of sanity is not the normality of the method but the reasonableness of the discovery. If Newton had been informed by Pythagoras that the moon was made of green cheese, then Newton would have been locked up. Gravitation, being a reasoned hypothesis which fitted remarkably well into the Copernican version of the observed ph

estion as between her and her comrades-in-arms. She gave this reason herself when she was pressed on the subject; and the fact that this entirely reasonable necessity came to her imagination first as an order from God delivered through the mouth of Saint Catherine does not prove that she was mad. The soundness of the order proves that she was unusually sane; but its form proves that her dramatic imagination played tricks with her senses. Her policy was also quite sound: nobody disputes