The key answer of exercise 6

In this quotation, Basil is suggesting that the true subject of a portrait is not the person being painted (the sitter) but the artist themselves. He implies that the sitter merely serves as a starting point or occasion for the artist to express their own inner world, emotions, and artistic vision. The painter’s style, technique, and personal perspective are what truly come through in the finished artwork, revealing more about the artist than about the sitter.