ch 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.

18. A good Measure of Time must divide its whole Duration into equal
Periods.

In the measuring of extension, there is nothing more required but the
application of the standard or measure we make use of to the thing of
whose extension we would be informed. But in the measuring of duration
this cannot be done, because no two different parts of succession can
be put together to measure one another. And nothing being a measure of
duration but duration, as nothing is of extension but extension, we
cannot keep by us any standing, unvarying measure of duration, which
consists in a constant fleeting succession, as we can of certain lengths
of extension, as inches, feet, yards, &c., marked out in permanent
parcels of matter. Nothing then could serve well for a convenient
measure of time, but what has divided the whole length of its duration
into apparently equal portions, by constantly repeated periods.
What portions of duration are not distinguished, or considered as
distinguished and measured, by such periods, come not so properly under
the notion of time; as appears by such phrases as these, viz. 'Before
all time,' and 'When time shall be no more.'

19. The Revolutions of the Sun and Moon, the properest Measures of Time
for mankind.

The diurnal and annual revolutions of the sun, as having been, from the
beginning of nature, constant, regular, and universally observable by
all mankind, and supposed equal to one another, have been with reason
made use of for the measure of duration. But the distinction of days
and years having depended on the motion of the sun, it has brought this
mistake with it, that it has been thought that motion and duration were
the measure one of another. For men, in the measuring of the length
of time, having been accustomed to the ideas of minutes, hours, days,
months, years, &c., which they found themselves upon any mention of
time or duration presently to think on, all which portions of time were
measured out by the motion of those heavenly bodies, they were apt to
confound time and motion; or at least to think that they had a necessary
connexion one with another. Whereas any constant periodical appearance,
or alteration of ideas,