He was haunted by ideas in which difference and unity appeared to be reconciled, recognising in this the impossibility at the heart of appearance. Time was one of the most typical of these. There is no experience of time, it is an idea, or more primitive than an idea, a form of synthesis of ideas. It seemed to need to be already at work in order to realise itself as flow and duration; the very term already being a curiously non-temporal metaphor for an essential component of the temporal. He pondered his concrete experiences of time: the time a pot of tea takes to brew, the time to set out to make a rendez-vous, the measurable time laid out in overlapping sequences of near repetitions that mark a progression or a delay towards an end, or the end; the time it takes to forget an action or a reaction, for it to fade and restore the screen to whiteness. Duration seemed to him a temporalisation of decay or decline, a running-off from brilliant and unconditioned presence. But then there were the odd temporal shadows cast by photographs and recordings with their hinted knowledge of death in life, or life in death, the unpronouncable message just for him.