only placed in a full light themselves, but may throw light on their
correspondent ideas, which lie in obscurity. And by this means, we may,
perhaps, attain a new microscope or species of optics, by which, in the
moral sciences, the most minute, and most simple ideas may be so
enlarged as to fall readily under our apprehension, and be equally known
with the grossest and most sensible ideas, that can be the object of
our enquiry.

[10] Section II.

50. To be fully acquainted, therefore, with the idea of power or
necessary connexion, let us examine its impression; and in order to find
the impression with greater certainty, let us search for it in all the
sources, from which it may possibly be derived.

When we look about us towards external objects, and consider the
operation of causes, we are never able, in a single instance, to
discover any power or necessary connexion; any quality, which binds the
effect to the cause, and renders the one an infallible consequence of
the other. We only find, that the one does actually, in fact, follow the
other. The impulse of one billiard-ball is attended with motion in the
second. This is the whole that appears to the _outward_ senses. The mind
feels no sentiment or _inward_ impression from this succession of
objects: Consequently, there is not, in any single, particular instance
of cause and effect, any thing which can suggest the idea of power or
necessary connexion.

From the first appearance of an object, we never can conjecture what
effect will result from it. But were the power or energy of any cause
discoverable by the mind, we could foresee the effect, even without