As his own painterly style evolved, what was important to Guardi in his views wasn't perspective, but the changing sky and the shimmering lagoon.

WSJ: Appreciating Francesco Guardi's Changing Genres/ A Guardi Retropsective at Museo Correr in Venice

After we passed under it, I also could hear the sound changing, dribbling into the wide sky above us.

CNN: 'On Looking': The world you're not seeing