What is mathematics about? And how can we have access to the reality it is supposed to describe? The book tells the story of this problem, first raised by Plato, through the views of Aristotle, Proclus, Kant, Frege, Gödel, Benacerraf, up to the most recent debate on mathematical platonism. MARCO PANZA is Research Professor at the CNRS. He is the author and editor of several books and papers in the domains of history and philosophy of mathematics. Including Analysis and sinthesis in Mathematics (ed., with M. Otte), 1997; Isaac Newton , 2003; Newton et l'origine de l'analyse, 1664-1666 , 2005; Nombres. Eléments de mathématiques pour philosophes , 2007. ANDREA SERENI is Lecturer at San Raffaele University, Milan, Italy. He has been a visiting scholar at Arché Centre at the University of St. Andrews. He has taught courses at the Universities of Modena and Reggio Emilia, Parma, and Bologna. His teaching, research and publications cover philosophy of mathematics, epistemology, and philosophy of language.