A similar structure can be discovered if we describe the experience of a melody. Each note in a melody has a musical quality which depends on the place of the note in a sequence of notes. We do not hear a note as an objective frequency but as the musical quality that fits in at that point in the melody. Indeed moving the whole tune up an octave does not change the experience of the melody, although the objective frequency of every note is changed. Each note is heard in the context of the previous (and anticipated) notes. That is, the previous notes are still present to consciousness when we hear the current note, otherwise it wouldn't be this note with this musical quality in this tune.
If we heard every note in isolation from the other notes of a melody, we couldn't experience a melody. That is, if our consciousness were punctual, each note would have a life of its own and wouldn't be part of a tune. We can only hear a tune if the previous notes somehow remain present while we are listening to the current note. This remaining-present is what Husserl calls retention. Similarly the note can only be experienced in its melodic quality if some future sequence of notes is at least vaguely anticipated in protention.
Imagine "God" listening in on a performance. "God" eternally hears all notes simultaneously. But this is not a melody, but a massive chord (or dischord!) Hence "God", not being capable of temporal experience, could never have the experience of hearing a tune (not even Gregorian chant.) [We are not speaking here of any real "God", but only of an abstract concept of a perfect entity to whom all moments are simultaneous.]
If everything we experience is actually present in the now, then either we could only hear one tone at a time, and so never hear a melody, or else we must hear the one note while recollecting the previous sequence. But recollection cannot solve our problem here. Imagine a conductor who asked you to recollect say, three note, and then played the fourth! Clearly this would not be the experience of a melody. Alternatively, if the conductor had no faith in your ability at retention and tried to solve the problem by playing all four notes at the same time, you would still not hear the melody. That is, the retained notes are neither actually present in the same mode as the current note, nor are they recollected. The experience cannot be adequately described as the addition to the actually present note of something else which is actually present, either another sounding note or another recollected note.
The previous notes which are retained are the self-same notes that we previously heard. I don't mean that they are copies of them, reproductions of them or representations of them. I mean that it is exactly the same note which was once sounding which is now experienced as present although past, indeed present as past.
The current note sinks into the past and is modified in this temporal fashion. It is now experienced as that past note which when it was current followed the previous note which is now the further-past, that which was already past when the previous note was actual. The retained past is not just homogenous, it has a layered structure with each phase being experienced as the past of another past. In a four note tune, when the fourth note is current, the second note is experienced not just as past, like the third note, but as the third note's immediate past.
Each note in a melody and each word in a sentence are, of course, themselves enduring, temporal objects in their own right, with a beginning, a middle and an end, and these phases need to be described in a similar manner. The whole note runs off as a unity, but it is the unity of a continuum, for even in the past the note never becomes a static object. Every retained now is a retention of previous nows, and each new moment is a modification of all of the previous retentions. Each note is a running-off continuum. A melody, as a continuum of notes, is then a continuum of continua. Time itself is, as Husserl puts it, "a continuum of continua." As we experience time in consciousness, it is a continual sinking- away, not a series of discrete points, although it is difficult for us to avoid this false impression when we try to put the phenomenon into words. There is a privileged point, the now, but consciousness is not restricted to this point; it embraces the whole articulated temporal structure. Indeed, if consciousness were not temporal in this way experience would not be possible