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supposed that there is a connexion between the present fact
and that which is inferred from it。 Were there nothing to
bind them together； the inference would be entirely
precarious。 The hearing of an articulate voice and rational
discourse in the dark assures us of the presence of some
person： Why？ because these are the effects of the human make
and fabric； and closely connected with it。 If we anatomize
all the other reasonings of this nature； we shall find that
they are founded on the relation of cause and effect； and
that this relation is either near or remote； direct or
collateral。 Heat and light are collateral effects of fire；
and the one effect may justly be inferred from the other。
If we would satisfy ourselves； therefore； concerning
the nature of that evidence； which assures us of matters of
fact； we must enquire how we arrive at the knowledge of
cause and effect。
I shall venture to affirm； as a general proposition；
which admits of no exception； that the knowledge of this
relation is not； in any instance； attained by reasonings ； but arises entirely from experience； when we find
that any particular objects are constantly conjoined with
each other。 Let an object be presented to a man of ever so
strong natural reason and abilities； if that object be
entirely new to him； he will not be able； by the most
accurate examination of its sensible qualities； to discover
any of its causes or effects。 A/DAM； though his rational
faculties be supposed； at the very first； entirely perfect；
could not have inferred from the fluidity and transparency
of water that it would suffocate him； or from the light and
warmth of fire that it would consume him。 No object ever
discovers； by the qualities which appear to the senses；
either the causes which produced it； or the effects which
will arise from it； nor can our reason； unassisted by
experience； ever draw any inference concerning real
existence and matter of fact。
This proposition； ； will readily
be admitted with regard to such objects； as we remember to
have once been altogether unknown to us； since we must be
conscious of the utter inability； which we then lay under；
of foretelling what would arise from them。 Present two
smooth pieces of marble to a man who has no tincture of
natural philosophy； he will never discover that they will
adhere together in such a manner as to require great force
to separate them in a direct line； while they make so small
a resistance to a lateral pressure。 Such events； as bear
little analogy to the common course of nature； are also
readily confessed to be known only by experience； nor does
any man imagine that the explosion of gunpowder； or the
attraction of a loadstone； could ever be discovered by
arguments 。 In like manner； when an effect is
supposed to depend upon an intricate machinery or secret
structure of parts； we make no difficulty in attributing all
our knowledge of it to experience。 Who will assert that he
can give the ultimate reason； why milk or bread is proper
nourishment for a man； not for a lion or a tyger？
But the same truth may not appear； at first sight； to
have the same evidence with regard to events； which have
become familiar to us from our first appearance in the
world； which bear a close analogy to the whole course of
nature； and which are supposed to depend on the simple
qualities of objects； without any secret structure of parts。
We are apt to imagine that we could discover these effects
by the mere operation of our reason； without experience。 We
fancy； that were we brought on a sudden into this world； we
could at first have inferred that one Billiard…ball would
communicate motion to another upon impulse； and that we
needed not to have waited for the event； in order to
pronounce with certainty concerning it。 Such is the
influence of custom； that； where it is strongest； it not
only covers our natural ignorance； but even conceals itself；
and seems not to take place； merely because it is found in
the highest degree。
But to convince us that all the laws of nature； and all
the operations of bodies without exception； are known only
by experience； the following reflections may； perhaps；
suffice。 Were any object presented to us； and were we
required to pronounce concerning the effect； which will
result from it； without consulting past observation； after
what manner； I beseech you； must the mind proceed in this
operation？ It must invent or imagine some event； which it
ascribes to the object as its effect； and it is plain that
this invention must be entirely arbitrary。 The mind can
never possibly find the effect in the supposed cause； by the
most accurate scrutiny and examination。 For the effect is
totally different from the cause； and consequently can never
be discovered in it。 Motion in the second Billiard…ball is a
quite distinct event from motion in the first； nor is there
any thing in the one to suggest the smallest hint of the
other。 A stone or piece of metal raised into the air； and
left without any support； immediately falls： But to consider
the matter ； is there any thing we discover in
this situation which can beget the idea of a downward；
rather than an upward； or any other motion； in the stone or
metal？
And as the first imagination or invention of a
particular effect； in all natural operations； is arbitrary；
where we consult not experience； so must we also esteem the
supposed tie or connexion between the cause and effect；
which binds them together； and renders it impossible that
any other effect could result from the operation of that
cause。 When I see； for instance； a Billiard…ball moving in a
straight line towards another； even suppose motion in the
second ball should by accident be suggested to me； as the
result of their contact or impulse； may I not conceive； that
a hundred different events might as well follow from that
cause？ May not both these balls remain at absolute rest？ May
not the first ball return in a straight line； or leap off
from the second in any line or direction？ All these
suppositions are consistent and conceivable。 Why then should
we give the preference to one； which is no more consistent
or conceivable than the rest？ All our reasonings
will never be able to show us any foundation for this
preference。
In a word； then； every effect is a distinct event from
its cause。 It could not； therefore； be discovered in the
cause； and the first invention or conception of it； ； must be entirely arbitrary。 And even after it is
suggested； the conjunction of it with the cause must appear
equally arbitrary； since there are always many other
effects； which； to reason； must seem fully as consistent and
natural。 In vain； therefore； should we pretend to determine
any single event； or infer any cause or effect； without the
assistance of observation and experience。
Hence we may discover the reason why no philosopher；
who is rational and modest； has ever pretended to assign the
ultimate cause of any natural operation； or to show
distin