  In addition to his work on the ontology of art objects of various kinds, Ingarden also undertook general work on the ontological status of the aesthetic object and the nature of aesthetic values, as well as phenomenological work on the experience of works of art of various kinds. On the object side, as we have seen he distinguishes in each case between the mere physical object and the work of art; but he also distinguishes both of these from what he calls the “concretization” (sometimes translated as “concretion”) of the work of art, which he considers to be the true ‘aesthetic object’. The work of art itself, in the case of most forms of art such as literature, painting, or music, is what Ingarden calls a “schematic formation.” That is, it has certain ‘places of indeterminacy’, many of which are filled in by an individual interpretation or ‘reading’ of the work. Thus in the case of literature, there are many places of indeterminacy at the level of character and plot — unlike in the case of real people, it is often simply indeterminate what a literary character had for breakfast, how far she sat back from the table, what the table was made of, etc. Such indeterminacies are generally partially filled in by the reader in reconstructing the work, as the reader’s background assumptions help (at least partially) flesh out the skeletal imaginary scene directly presented by the words of the text. Similarly, a representational painting generally leaves indeterminate, e.g., what the back of the person’s head looks like in the case of a portrait, what they are thinking, or what happens immediately before or after the moment visually represented in paintings of historical events. Yet again, viewers’ reconstructive acts typically supplement these indeterminacies in various ways, e.g. automatically grasping the lower right corner of Breugel’s ‘Fall of Icarus’ as presenting the moment between a fall from the sky and the complete disappearance of the body under water (not, e.g., as presenting an attempt at an underwater handstand). Finally, in the case of music, a score leaves indeterminate various elements such as the precise timbre and fullness of tone, and these are filled out in different ways in different performances of the work. In each case, (at least partially) filling in the indeterminacies of the work through a reading, performance, or viewing renders the work more ‘concrete’. Each work of art permits of a variety of legitimate concretizations which, unlike the work of art itself, may vary from viewer to viewer. If the concretion occurs within the aesthetic attitude, an aesthetic object is formed [Selected Papers, 93], and so many aesthetic objects may be based on one and the same work of art.