Suppose we met Euclid on Westminster Bridge, and he took us aside and confessed to us that whilst he regarded parallelograms and rhomboids with an indifference bordering on contempt, for isosceles triangles he cherished a wild romantic devotion. Suppose he asked us to accompany him to the nearest music-shop, and there purchased a guitar in order that he might worthily sing to us the radiant beauty and the radiant goodness of isosceles triangles. As men we should, I hope, respect his enthusiasm, and encourage his enthusiasm, and catch his enthusiasm. But as seekers after truth we should be compelled to regard with a dark suspicion, and to check with the most anxious care, every fact that he told us about isosceles triangles.
