  Brentano’s views on these matters underwent several changes. In his earlier writings, he held that proteraestheses are filled with non-existent (purely intentional) objects; the latter are apprehended under a ‘modifying attribute’ which results in their (seemingly) possessing a certain degree of pastness. He came to view this is as mistake, and in later writings he argued that the difference between the content of a proteraesthesis and an ordinary (present) sensation lies not in the nature of the object of which we are aware, but rather the way in which we are aware of it – there are ‘temporal modes of consciousness’. Initially he construed these temporal modes in terms of differences in judgement (a represented content a is judged be past to a certain degree); in the final phase of his thought he opted instead for temporal modes of presentation: sensory objects can be apprehended as past to differing degrees. See Chisholm (1981) and Kraus (1976) for further details.