I fight a running battle with the focal point issue.
"But Rousseau was innovative in other respects, too. He developed a radically different approach to landscape composition ... Here there are neither framing devices nor a central point of focus for the eye to settle on. Instead, the emphatic horizontality of the canvas -- a typical Rousseauesque device -- coupled with the broad, half-and-half division between earth and sky and the introduction of a secondary, false horizon between flat and rocky terrain, generates a strong feeling of a world that is endlessly scanned rather than simply looked at. This feeling is further reinforced by a parade of small pictorial incidents, moving left to right and right to left across the middle ground of the picture, where most of the sunlight is falling."
Theodore Rousseau, "The Gorges d'Apremont at Midday" in How to Read a Modern Painting