  The horizontal line a-b-c-d corresponds to a continuous flow of ongoing auditory sensations; the vertical lines correspond to the proteraestheses which accompany these sensations at three particular points b, c an d. As can be seen, as we move from b to c to d, the proteraestheses gradually increase in complexity, with the result that the hearing of d is accompanied by representations of preceding tone-phases stretching right back to a, but no further: this is the limit of the experienced present. Although in this last episode representations of a, b and c are experienced together with d, these tone-phases are not experienced as simultaneous – i.e., as a chord – rather, they are experienced as a succession. This gives rise to several questions. How can contents which are simultaneous, objectively speaking, seem to be successive? What is the precise nature of the representations occurring in proteraestheses?