A mathematician, like a painter or a poet, is a maker of patterns. If his patterns are more permanent than theirs, it is because they are made with ideas. A painter makes patterns with shapes and colours, a poet with words. A painter may embody an idea,´ but the idea is usually commonplace and unimportant. In poetry, ideas count for a great deal more; but as Housman insisted, the importance of ideas in poetry is habitually exaggerated... A mathematician, on the other hand, has no material to work with but ideas, and so his patterns are likely to last longer, since ideas wear less with time than words. The mathematician´s patterns, like the painter´s or the poet´s, must be beautiful; the ideas, like the colors or the words, must ?t together in a harmonious way. Beauty is the ?rst test: there is no permanent place in the world for ugly mathematics. -G.H.Hardy, A Mathematician´s Apology, 1940 [Har, pp. 24-25] I grew up on books by Isaac M. Yaglom and Vladimir Bolty- ski. I read their books as a middle and high school student in Moscow. During my college years, I got to know Isaak Moiseevich Yaglom personally and treasured his passion for and expertise in geometry and ?ne art. In the midst of my xxv xxvi Preface college years, a group of Moscow mathematicians, including Isaak Yaglom, signed a letter protesting the psychiatric - prisonment of the famous dissident Alexander Esenin-Volpin.
