This lecture turns to the brief but seismic career of Masaccio, the painter who translated the structural logic of Brunelleschi and the emotional weight of Donatello onto the two-dimensional surface. We will examine his radical departure from the ornamental International Gothic style, focusing on his pioneering use of one-point linear perspective in the Holy Trinity to create a convincing illusion of depth that pierced the church wall. The session will also explore the Brancacci Chapel frescoes, particularly The Tribute Money and The Expulsion from the Garden of Eden, where his mastery of directional light (chiaroscuro) and atmospheric perspective endowed figures with a sculptural mass and psychological presence previously unseen in Italian painting. By analysing these masterpieces, we will establish how Masaccio set the standard for narrative realism that would guide Western art for centuries.