Few artists of the fifteenth century are as revered today as Piero della Francesca (c.1413-92). The favourite artist of many painters and sculptors of our own time, he is admired especially for the balance of his compositions, the geometric perfection of his forms and the emotional coolness of his style. The secret of these qualities lies in part in Piero's achievements as a mathematician, one of the greatest of his age, and the author of...