This thesis analyzes Cézanne's paintings from around the date 1878 and the impact of the text by Stendhal, L'Histoire de la Peinture en Italie, on Cézanne's theory and practice. Interpreting Cézanne's paintings from 1878 in light of this connection, offers a new understanding of the shift that occurred in Cézanne's oeuvre with his invention of the "constructive brushstroke" method. With this shift Cézanne broke with the Impressionist style and became the painter celebrated by many as the father of modernist painting in the 20th century. Stendhal has been overlooked by most Cézanne scholars and certainly has never been seen as essential to the painter's process of developing the "constructive brushstroke." In three chapters, I will include key insights from Cézanne scholarship, Cézanne's own thoughts on painting and their impact on his art. Discussed in tandem with the Stendhal connection, these observations can deepen the understanding of Cézanne's theory and practice.