 On this basis, he rejects the identification of musical works with ideal objects, such as mathematical entities, for musical works come into existence when they are first composed (Ingarden 1973 [1986: 15]; a phenomenological account of musical works as ideal objects had been proposed by Waldemar Conrad (1878–1915) (1908), whose view Ingarden explicitly challenges). Works of music cannot be identified with their score either, as they can be composed without being notated and may even exist in the complete absence of notational systems (Ingarden 1973 [1986: 38]). Ingarden holds instead that musical works are intentional objects. While they require an experiencing subject, they cannot be identified with particular subjective experiences. This also accounts for the temporality that is characteristic of musical works. While a work’s performance is extended in time, the work itself is not a temporal object. It merely specifies an order of succession between its elements. The musical work is thus “quasi-temporal” (Ingarden 1973 [1986: 70]). Ingarden also accounts for the apparent change of a work through time, a change that may seem evident when one considers the radical differences in the performance of the same work at different historical times. However, insofar as the set of legitimate interpretations of a work is determined by its score, this change is one not in the work itself, but merely in what is considered valuable about it (Ingarden 1973 [1986: 156]) (on Ingarden’s musical ontology, see Mitscherling 1997: chapter 5).