  Brentano has rather more to say on this issue. We saw earlier (§2.4) that Brentano was the first to expound a Modal Retentional model in any detail, and that his views went through several changes. Initially he sought to explain the difference between present sensations and proteraestheses (in effect, retentions) in terms of different kinds of experiential objects: he held that proteraestheses are composed of intentionally unreal objects that are apprehended under a ‘modifying attribute’ of a (certain degree) of pastness. He came to view this as an error, in part because he believed past, present and future form a continuum, a view which is difficult to hold onto if present experiences are real, and past and future ones are not. In later writings he suggested that the difference between the contents of an ordinary sensation and a proteraesthesis is to be located in the way we are aware of them. He first explicated these differences in temporal modes in terms of differences in judgement : a represented content a is judged be past to a certain degree, a content b is judged to be past to a greater degree, and so forth. In a further change of view he rejected judgements in favour of temporal modes of presentation: sensory objects can be apprehended as past to differing degrees. In his essay ‘Our intuition of Time is a Continuum of Modes of Presentation and Acceptance’ he writes: