 Granger’s analysis of mathematical style takes up chapters 2, 3, and 4 of his book. Chapter 2 deals with Euclidean style and the notion of magnitude; chapter 3 with the opposition between ‘Cartesian style and Desarguian style’ (on the Cartesian style see also Rabouin 2017); finally, chapter 4 concerns the ‘birth of vectorial style’. All of these analyses center around the concept of “geometrical magnitude”.