But it is evident, in the first place, that the repetition of like
objects in like relations of succession and contiguity discovers
nothing new in any one of them: since we can draw no inference from it,
nor make it a subject either of our demonstrative or probable
reasonings;[16] as has been already proved. Nay suppose we could draw
an inference, it would be of no consequence in the present case; since
no kind of reasoning can give rise to a new idea, such as this of power
is; but wherever we reason, we must antecedently be possest of clear
ideas, which may be the objects of our reasoning. The conception always
precedes the understanding; and where the one is obscure, the other is
uncertain; where the one fails, the other must fail also.
[16] Sect. 6.
Secondly, It is certain that this repetition of similar objects in
similar situations produces nothing new either in these objects, or
in any external body. For it will readily be allowed, that the several
instances we have of the conjunction of resembling causes and effects
are in themselves entirely independent, and that the communication
of motion, which I see result at present from the shock of two
billiard-balls, is totally distinct from that which I saw result from
such an impulse a twelve-month ago. These impulses have no influence
on each other. They are entirely divided by time and place; and the one
might have existed and communicated motion, though the other never had
been in being.
There is, then, nothing new either discovered or produced in any objects
by their constant conjunction, and by the uninterrupted resemblance
of their relations of succession and contiguity. But it is from this
resemblance, that the ideas of necessity, of power, and of efficacy, are
derived. These ideas, therefore, represent not anything, that does or
can belong to the objects, which are constantly conjoined. This is
an argument, which, in every view we can examine it, will be found
perfectly unanswerable. Similar instances are still the first source
of our idea of power or necessity; at the same time that they have no
influence by their similarity either on each other, or on any external
object. We must, therefore, turn ourselves to some other quarter to seek
the origin of that idea.