From these phenomena, as well as from many others, we may conclude, that time cannot make its appearance to the mind, either alone, or attended with a steady unchangeable object, but is always discovered some PERCEIVABLE succession of changeable objects.
To confirm this we may add the following argument, which to me seems perfectly decisive and convincing.

It is evident, that time or duration consists of different parts: For otherwise we coued not conceive a longer or shorter duration.

It is also evident, that these parts are not co-existent: For that quality of the co-existence of parts belongs 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.