reality； there is scarcely a proposition in E/UCLID so
simple； as not to consist of more parts； than are to be
found in any moral reasoning which runs not into chimera and
conceit。 Where we trace the principles of the human mind
through a few steps； we may be very well satisfied with our
progress； considering how soon nature throws a bar to all
our enquiries concerning causes； and reduces us to an
acknowledgment of our ignorance。 The chief obstacle；
therefore； to our improvement in the moral or metaphysical
sciences is the obscurity of the ideas； and ambiguity of the
terms。 The principal difficulty in the mathematics is the
length of inferences and compass of thought； requisite to
the forming of any conclusion。 And； perhaps； our progress in
natural philosophy is chiefly retarded by the want of proper
experiments and phaenomena； which are often discovered by
chance； and cannot always be found； when requisite； even by
the most diligent and prudent enquiry。 As moral philosophy
seems hitherto to have received less improvement than either
geometry or physics； we may conclude； that； if there be any
difference in this respect among these sciences； the
difficulties； which obstruct the progress of the former；
require superior care and capacity to be surmounted。
There are no ideas； which occur in metaphysics； more
obscure and uncertain； than those of ； ；
or ； of which it is every
moment necessary for us to treat in all our disquisitions。
We shall； therefore； endeavour； in this section； to fix； if
possible； the precise meaning of these terms； and thereby
remove some part of that obscurity； which is so much
complained of in this species of philosophy。
It seems a proposition； which will not admit of much
dispute； that all our ideas are nothing but copies of our
impressions； or； in other words； that it is impossible for
us to of any thing； which we have not antecedently
； either by our external or internal senses。 I have
endeavoured＇15＇ to explain and prove this proposition； and
have expressed my hopes； that； by a proper application of
it； men may reach a greater clearness and precision in
philosophical reasonings； than what they have hitherto been
able to attain。 Complex ideas； may； perhaps； be well known
by definition； which is nothing but an enumeration of those
parts or simple ideas； that compose them。 But when we have
pushed up definitions to the most simple ideas； and find
still more ambiguity and obscurity； what resource are we
then possessed of？ By what invention can we throw light upon
these ideas； and render them altogether precise and
determinate to our intellectual view？ Produce the
impressions or original sentiments； from which the ideas are
copied。 These impressions are all strong and sensible。 They
admit not of ambiguity。 They are not 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。
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 senses。 The mind feels no sentiment or
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 experience； and
might； at first； pronounce with certainty concerning it； by
mere dint of thought and reasoning。
In reality； there is no part of matter； that does ever；
by its sensible qualities； discover any power or energy； or
give us ground to imagine； that it could produce any thing；
or be followed by any other object； which we could
denominate its effect。 Solidity； extension； motion； these
qualities are all complete in themselves； and never point
out any other event which may result from them。 The scenes
of the universe are continually shifting； and one object
follows another in an uninterrupted succession； but the
power of force； which actuates the whole machine； is
entirely concealed from us； and never discovers itself in
any of the sensible qualities of body。 We know that； in
fact； heat is a constant attendant of flame； but what is the
connexion between them； we have no room so much as to
conjecture or imagine。 It is impossible； therefore； that the
idea of power can be derived from the contemplation of
bodies； in single instances of their operation； because no
bodies ever discover any power； which can be the original of
this idea。＇16＇
Since； therefore； external objects as they appear to
the senses； give us no idea of power or necessary connexion；
by their operation in particular instances； let us see；
whether this idea be derived from reflection on the
operations of our own minds； and be copied from any internal
impression。 It may be said； that we are every moment
conscious of internal power； while we feel； that； by the
simple command of our will； we can move the organs of our
body； or direct the faculties of our mind。 An act of
volition produces motion in our limbs； or raises a new idea
in our imagination。 This influence of the will we know by
consciousness。 Hence we acquire the idea of power or energy；
and are certain； that we ourselves and all other intelligent
beings are possessed of power。 This idea； then； is an idea
of reflection； since it arises from reflecting on the
operations of our own mind； and on the command which is
exercised by will； both over the organs of the body and
faculties of the soul。
We shall proceed to examine this pretension； and first
with regard to the influence of volition over the organs of
the body。 This influence； we may observe； is a fact； which；
like all other natural events； can be known only by
experience； and can never be foreseen from any apparent
energy or power in the cause； which connects it with the
effect； and renders the one an infallible consequence of the
other。 The motion of our body follows upon the command of
our will。 Of this we are every moment conscious。 But the
means； by which this is effected； the energy； by which the
will performs so extraordinary an operation； of this we are
so far from being immediately conscious； that it must for
ever escape our most diligent enquiry。
For ； is there any principle in all nature more
mysterious than the union of soul with body； by which a
supposed spiritual substance acquires such an influence over
a material one； that the most refined thought is able to
actuate the grossest matter？ Were we empowered； by a secret
wish； to remove mountains； or control the planets in their
orbit； this extensive authority would not be more
extraordinary； nor more beyond our comprehension。 But if by
consciousness we perceived any power or energy in the will；
we must know this power； we must know its connexion with the
effect； we must know the secret union of soul and body； and
the nature of both these substances； by which the one is
able to operate； in so many instances； upon the other。
； We are not able to move all the organs of
the body with a like authority； though we cannot assign any
reason besides experience； for so remarkable a difference
between one and the other。 Why has the will an influence
over the tongue and fingers； not over the heart or liver？
This question would never embarrass us； were we conscious of
a power in the former case； not in the latter。 We should
then perceive； independent of experience； why the authority
of will over the organs of the body is circumscribed within
such particular limits。 Being in that case fully acquainted
with the power or force； by which it operates； we should
also know； why its influence reaches precisely to such
boundaries； and no farther。
A man； suddenly struck with palsy in the leg or arm； or
who had newly lost those members； frequently endeavours； at
first to move them； and employ them； in their usual offices。
Here he is as much conscious of power to command such limbs；
as a man in perfect hea