ongs to
extension, and is what distinguishes it from duration. Now as time is
composed of parts, that are not coexistent: an unchangeable object,
since it produces none but coexistent impressions, produces none that
can give us the idea of time; and consequently that idea must be
derived from a succession of changeable objects, and time in its first
appearance can never be severed from such a succession.

Having therefore found, that time in its first appearance to the mind
is always conjoined with a succession of changeable objects, and that
otherwise it can never fall under our notice, we must now examine
whether it can be conceived without our conceiving any succession
of objects, and whether it can alone form a distinct idea in the
imagination.

In order to know whether any objects, which are joined in impression,
be inseparable in idea, we need only consider, if they be different
from each other; in which case, it is plain they may be conceived apart.
Every thing, that is different is distinguishable: and everything,
that is distinguishable, may be separated, according to the maxims
above-explained. If on the contrary they be not different, they are
not distinguishable: and if they be not distinguishable, they cannot be
separated. But this is precisely the case with respect to time, compared
with our successive perceptions. The idea of time is not derived from a
particular impression mixed up with others, and plainly distinguishable
from them; but arises altogether from the manner, in which impressions
appear to the mind, without making one of the number. Five notes played
on a flute give us the impression and idea of time; though time be not
a sixth impression, which presents itself to the hearing or any other of
the senses. Nor is it a sixth impression, which the mind by reflection
finds in itself. These five sounds making their appearance in this
particular manner, excite no emotion in the mind, nor produce an
affection of any kind, which being observed by it can give rise to a new
idea. For that is necessary to produce a new idea of reflection, nor can
the mind, by revolving over a thousand times all its ideas of sensation,
ever extract from them any new original idea, unless nature has so
framed its faculties, that it feels some new original impression arise
from such a contemplation. But here it only takes notice of the manner,
in which the different sounds make their appearance; and that it may
afterwards