next question, then, should naturally be, how experience gives rise to
such a principle? But as I find it will be more convenient to sink this
question in the following, Why we conclude, that such particular causes
must necessarily have such particular erects, and why we form an
inference from one to another? we shall make that the subject of our
future enquiry. It will, perhaps, be found in the end, that the same
answer will serve for both questions.



SECT. IV. OF THE COMPONENT PARTS OF OUR REASONINGS CONCERNING
CAUSE AND EFFECT.


Though the mind in its reasonings from causes or effects carries its view
beyond those objects, which it sees or remembers, it must never lose
sight of them entirely, nor reason merely upon its own ideas, without
some mixture of impressions, or at least of ideas of the memory, which
are equivalent to impressions. When we infer effects from causes, we must
establish the existence of these causes; which we have only two ways of
doing, either by an immediate perception of our memory or senses, or by
an inference from other causes; which causes again we must ascertain in
the same manner, either by a present impression, or by an inference from
their causes, and so on, till we arrive at some object, which we see or
remember. It is impossible for us to carry on our inferences IN INFINITUM;
and the only thing, that can stop them, is an impression of the memory or
senses, beyond which there is no room for doubt or enquiry.

To give an instance of this, we may chuse any point of history, and
consider for what reason we either believe or reject it. Thus we believe