  Hartmann’s central thesis on the ontology of art is that works are fictions that depend upon the perceptual and imaginative activities of artists and their audiences. In Hartmann’s view, the work of art has at least two parts or strata: the first layer, which he sometimes refers to as the “foreground,” is perceptible—Hartmann’s examples include a piece of stone, colors on a surface, and audible sounds. The perception of such items is the basis of the aesthetic experience of the higher “background” stratum, which also requires imaginings occasioned by this perceptual experience. The artistic and aesthetic qualities of the work arise from the relation between these ‘heterogeneous’ levels. Hartmann’s discussion of the artwork’s strata resembles some of the claims made by Ingarden. It would appear that the two philosophers arrived at these results independently; for a comparison of their positions, see Wolfgang Ruttkowski (1990).