The impressionist artist began as Realists. Their main subject was light and color. They painted landscapes at various times of day and atmospheric conditions. The changing light patterns became their subject matter.
Objects appear different as the times of day changes.
Notice the object again at noon, the colors are more vibrant and intense. The evening perhaps creates cool shadows of deep penetrating colors. Detailed analysis was not the goal of the impressionist. Rather, quick, loose, brush strokes revealed an instant impression. There is a sketchy quality to their work.