after we have experience of the operations of
cause and effect, our conclusions from that experience are _not_ founded
on reasoning, or any process of the understanding.

The bread which I formerly ate nourished me; that is, a body of such
sensible qualities was at that time endued with such secret powers; but
does it follow that other bread must also nourish me at another time,
and that like sensible qualities must always be attended with like
secret powers? The consequence seems nowise necessary. At least, it must
be acknowledged that there is here a consequence drawn by the mind, that
there is a certain step taken; a process of thought, and an inference
which wants to be explained.

These two propositions are far from being the same: "I have found that
such an object has always been attended with such an effect," and: "I
foresee that other objects, which are in appearance similar, will be
attended with similar effects." I shall allow, if you please, that the
one proposition may justly be inferred from the other; I know, in fact,
that it always is inferred. But you must confess that the inference is
not intuitive; neither is it demonstrative. Of what nature is it, then?
To say it is experimental is begging the question. For all inferences
from experience suppose, as their foundation, that the future will
resemble the past, and that similar powers will be conjoined with
similar sensible qualities.

If there be any suspicion that the course of nature may change, and that
the past may be no rule for the future, all experience becomes useless,
and can give rise to no inference or conclusion. It is impossible,
therefore, that any arguments from experience can prove this resemblance
of the past to the future, since all these arguments are founded on the
supposition of that resemblance. Let the course of things be allowed
hitherto ever so regular, that alone, without some new argument or
inference, proves not that for the future it will continue so. In vain
do you pretend to have learned the nature of bodies from your past
experience. Their secret nature, and consequently all their effects and
influence, may change without any change in their sensible qualities.
This happens sometimes, and with regard to some objects. Why may it not
happen always, and with regard to all objects? What logic, what process
of argument, secures you against this supposition? My practice, you say,
refutes my doubts. But you mistake the purport