17. Time is duration set out by measures.
Having thus got the idea of duration, the next thing natural for the mind
to do, is to get some measure of this common duration, whereby it might judge of its different lengths, and
consider the distinct order wherein several things exist; without which a great part of our knowledge would be
confused, and a great part of history be rendered very useless. This consideration of duration, as set out by certain
periods, and marked by certain measures or epochs, is that, I think, which most properly we call time.