““Brother Luca Pacioli. It took him thirty years to write.” The book is bound in deepest green with a tooled border of gold, and its pages are edged in gilt, so that it blazes in the light. Its clasps are studded with blackish garnets, smooth, translucent. “I hardly dare open it,” the boy says. “Please. You will like it.” It is Summa de Arithmetica. He unclasps it to find a woodcut of the author with a book before him, and a pair of compasses.””
