Robert Rosen wrote:
"I will begin by stepping back a bit, by supposing that we do not yet have a notion of state at our disposal. In effect, I will retreat to the level of percepts and perceptions and treat the self as a pure observer. The idea of state, being a concept and not a percept, thus does not yet enter the picture at all. Thus, all we have is the self looking out at its ambience. What does it see?
All the self can see is a sequence of percepts, ordered by its subjective sense of time. We suppose that the self can choose which percepts it will look at (in more sophisticated language, which variables it will measure) and whether it will look continuously or sample at discrete intervals. (Subjective) time is itself a complicated concept (see AS), but it is a primitive that we can take for granted at this level. Thus, the result of the self looking at its ambience is only a tabulation; a list of what is seen, indexed by when it is seen. Such a list we shall call a chronicle.
Chronicles can thus be completely arbitrary things, at least insofar as what is tabulated in them is concerned. Weather bureaus, stock exchanges, census takers, and a host of other familiar institutions provide endless streams of them. In the scientific realm, they are data. To the historian, entirely concerned with what happened when, they are the very stuff of existence.