Bartlett Pear is an example of Chiaroscuro-light and shadow. There is a thin transparent shadow and a thick impasto for the lights in this painting. Everything in the painting except the light is background for the painting including the shadow in the pear. Squint your eyes. Everything except the light is the same value (degree of lightness or darkness) or close to the same value. This serves as a foil for the light falling on the nooks and crannies of the pear. This same concept would apply if I were painting a portrait. Try super-imposing a face onto the pear. Get the picture?