d prior to another, without being considered
as its cause. There is a NECESSARY CONNEXION to be taken into
consideration; and that relation is of much greater importance, than any
of the other two above-mentioned.

Here again I turn the object on all sides, in order to discover
the nature of this necessary connexion, and find the impression, or
impressions, from which its idea may be derived. When I cast my eye on
the known Qualities of objects, I immediately discover that the relation
of cause and effect depends not in the least on them. When I consider
their relations, I can find none but those of contiguity and succession;
which I have already regarded as imperfect and unsatisfactory. Shall the
despair of success make me assert, that I am here possest of an idea,
which is not preceded by any similar impression? This would be too
strong a proof of levity and inconstancy; since the contrary principle
has been already so firmly established, as to admit of no farther doubt;
at least, till we have more fully examined the present difficulty.

We must, therefore, proceed like those, who being in search of any
thing, that lies concealed from them, and not finding it in the place
they expected, beat about all the neighbouring fields, without any
certain view or design, in hopes their good fortune will at last guide
them to what they search for. It is necessary for us to leave the
direct survey of this question concerning the nature of that necessary
connexion, which enters into our idea of cause and effect; and endeavour
to find some other questions, the examination of which will perhaps
afford a hint, that may serve to clear up the present difficulty. Of
these questions there occur two, which I shall proceed to examine, viz.

First, For what reason we pronounce it necessary, that every thing whose
existence has a beginning, should also have a cause.

Secondly, Why we conclude, that such particular causes must necessarily
have such particular effects; and what is the nature of that inference
we draw from the one to the other, and of the belief we repose in it?

I shall only observe before I proceed any farther, that though the ideas
of cause and effect be derived from the impressions of reflection as
well as from those of sensation, yet for brevity's sake, I commonly
mention only the latter as the origin of these ideas; though I desire
that whatever I say of them may also extend to the former. Passions are
connected with