 Granger’s Essay of a philosophy of style (Essai d’une philosophie du style 1968) is the most systematic and worked-out effort to develop a theory of style for mathematics. Granger’s program is so ambitious and rich that a thorough discussion of the structure of his book and of his detailed analyses would need a paper by itself (see also Benis-Sinaceur 2010). Due to limitation of space, the aim here is to give just a rough idea of what the project consists in and to show that the epistemological role of style defended by Ganger is compatible with a realism about mathematical entities or structures. 