What idea did Albert introduce in his famous artwork theory On Painting?

In his theory "On Painting," Albert introduced the idea that painting should be viewed as a form of representation that captures the essence of reality through a structured composition. He emphasized the importance of perspective, light, and color in creating a sense of depth and realism, arguing that these elements work together to engage the viewer's perception. Albert also advocated for the artist's role as a mediator between nature and the observer, suggesting that art should evoke emotions and provoke thought.