The Internet Wiretap online edition of

            AN ENQUIRY CONCERNING
             HUMAN UNDERSTANDING

                     by
                 DAVID HUME

          Harvard Classics Volume 37
      Copyright 1910 P.F. Collier & Son

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SECTION I
OF THE DIFFERENT SPECIES OF PHILOSOPHY.

  MORAL philosophy, or the science of human nature, 
may be treated after two different manners; each 
of which has its peculiar merit, and may contribute 
to the entertainment, instruction, and reformation of man- 
kind. The one considers man chiefly as born for action; 
and as influenced in his measures by taste and sentiment; 
pursuing one object, and avoiding another, according to 
the value which these objects seem to possess, and accord- 
ing to the light in which they present themselves. As vir- 
tue, of all objects, is allowed to be the most valuable, this 
species of philosophers paint her in the most amiable 
colours; borrowing all helps from poetry and eloquence, and 
treating their subject in an easy and obvious manner, and 
such as is best fitted to please the imagination, and engage 
the affections. They select the most striking observations 
and instances from common life; place opposite characters 
in a proper contrast; and alluring us into the paths of virtue 
by the views of glory and happiness, direct our steps in 
these paths by the soundest precepts and most illustrious 
examples. They make us feel the difference between vice 
and virtue; they excite and regulate our sentiments; and 
so they can but bend our hearts to the love of probity and 
true honour, they think, that they have fully attained the 
end of all their labours. 

  The other species of philosophers consider man in the 
light of a reasonable rather than an active being, and 
endeavour to form his understanding more than cultivate 
his manners. They regard human nature as a subject of 
speculation; and with a narrow scrutiny examine it, in 
order to find those principles, which regulate our under- 
standing, excite our sentiments, and make us approve or 
blame any particular object, action, or behaviour. They 
think it a reproach to all literature, that philosophy should 
not yet have fixed, beyond controversy, the foundation of 
morals, reasoning, and criticism; and should for ever talk 
of truth and falsehood, vice and virtue, beauty and de- 
formity, without being able to determine the source of 
these distinctions. While they attempt this arduous task, 
they are deterred by no difficulties; but proceeding from 
particular instances to general principles, they still push on 
their enquiries to principles more general, and rest not 
satisfied till they arrive at those original principles, by 
which, in every science, all human curiosity must be 
bounded. Though their speculations seem abstract, and 
even unintelligible to common readers, they aim at the 
approbation of the learned and the wise; and think them- 
selves sufficiently compensated for the labour of their whole 
lives, if they can discover some hidden truths, which may 
contribute to the instruction of posterity. 

  It is certain that the easy and obvious philosophy will 
always, with the generality of mankind, have the preference 
above the accurate and abstruse; and by many will be 
recommended, not only as more agreeable, but more useful 
than the other. It enters more into common life; moulds 
the heart and affections; and, by touching those principles 
which actuate men, reforms their conduct, and brings them 
nearer to that model of perfection which it describes. On 
the contrary, the abstruse philosophy, being founded on a 
turn of mind, which cannot enter into business and action, 
vanishes when the philosopher leaves the shade, and comes 
into open day; nor can its principles easily retain any in- 
fluence over our conduct and behaviour. The feelings of 
our heart, the agitation of our passions, the vehemence of 
our affections, dissipate all its conclusions, and reduce the 
profound philosopher to a mere plebeian. 

  This also must be confessed, that the most durable, 
as well as justest fame, has been acquired by the easy 
philosophy, and that abstract reasoners seem hitherto to 
have enjoyed only a momentary reputation, from the caprice 
or ignorance of their own age, but have not been able 
to support their renown with more equitable posterity. It 
is easy for a profound philosopher to commit a mistake 
in his subtile reasonings; and one mistake is the necessary 
parent of another, while he pushes on his consequences, 
and is not deterred from embracing any conclusion, by 
its unusual appearance, or its contradiction to popular 
opinion. But a philosopher, who purposes only to represent 
the common sense of mankind in more beautiful and more 
engaging colours, if by accident he falls into error, goes no 
farther; but renewing his appeal to common sense, and the 
natural sentiments of the mind, returns into the right path, 
and secures himself from any dangerous illusions. The 
fame of Cicero flourishes at present; but that of Aristotle 
is utterly decayed. La Bruyere passes the seas, and still 
maintains his reputation: but the glory of Malebranche 
is confined to his own nation, and to his own age. And 
Addison, perhaps, will be read with pleasure, when Locke 
shall be entirely forgotten. 

  The mere philosopher is a character, which is commonly 
but little acceptable in the world, as being supposed to 
contribute nothing either to the advantage or pleasure 
of society; while he lives remote from communication with 
mankind, and is wrapped up in principles and notions equally 
remote from their comprehension. On the other hand, 
the mere ignorant is still more despised; nor is any thing 
deemed a surer sign of an illiberal genius in an age and 
nation where the sciences flourish, than to be entirely 
destitute of all relish for those noble entertainments. The 
most perfect character is supposed to lie between those 
extremes; retaining an equal ability and taste for books, 
company, and business; preserving in conversation that 
discernment and delicacy which arise from polite letters; 
and in business, that probity and accuracy which are 
the natural result of a just philosophy. In order to diffuse 
and cultivate so accomplished a character, nothing can be 
more useful than compositions of the easy style and manner, 
which draw not too much from life, require no deep appli- 
cation or retreat to be comprehended, and send back the 
student among mankind full of noble sentiments and wise 
precepts, applicable to every exigence of human life. By 
means of such compositions, virtue becomes amiable, 
science agreeable, company instructive, and retirement en- 
tertaining. 

  Man is a reasonable being; and as such, receives from 
science his proper food and nourishment: But so narrow 
are the bounds of human understanding, that little satisfac- 
tion can be hoped for in this particular, either from the 
extent of security or his acquisitions. Man is a sociable, no 
less than a reasonable being: but neither can he always 
enjoy company agreeable and amusing, or preserve the 
proper relish for them. Man is also an active being; and 
from that disposition, as well as from the various necessities 
of human life, must submit to business and occupation: 
but the mind requires some relaxation, and cannot always 
support its bent to care and industry. It seems, then, that 
nature has pointed out a mixed kind of life as most suitable 
to the human race, and secretly admonished them to allow 
none of these biases to draw too much, so as to incapacitate 
them for other occupations and entertainments. Indulge 
your passion for science, says she, but let your science be 
human, and such as may have a direct reference to action 
and society. Abstruse thought and profound researches I 
prohibit, and will severely punish, by the pensive melancholy 
which they introduce, by the endless uncertainty in which 
they involve you, and by the cold reception which your 
pretended discoveries shall meet with, when communicated. 
Be a philosopher; but, amidst all your philosophy, be still 
a man. 

  Were the generality of mankind contented to prefer the 
easy philosophy to the abstract and profound, without 
throwing any blame or contempt on the latter, it might 
not be improper, perhaps, to comply with this general 
opinion, and allow every man to enjoy, without opposition, 
his own taste and sentiment. But as the matter is often 
carried farther, even to the absolute rejecting of all pro- 
found reasonings, or what is commonly called metaphysics, 
we shall now proceed to consider what can reasonably be 
pleaded in their behalf. 

  We may begin with observing, that one considerable 
advantage, which results from the accurate and abstract 
philosophy, is, its subserviency to the easy and humane; 
which, without the former, can never attain a sufficient 
degree of exactness in its sentiments, precepts, or reasonings. 
All polite letters are nothing but pictures of human life 
in various attitudes and situations; and inspire us with 
different sentiments, of praise or blame, admiration or ridi- 
cule, according to the qualities of the object, which they set 
before us. An artist must be better qualified to succeed in 
this undertaking, who, besides a delicate taste and a quick 
apprehension, possesses an accurate knowledge of the in- 
ternal fabric, the operations of the understanding, the 
workings of the passions, and the various species of senti- 
ment which discriminate vice and virtue. How painful 
soever this inward search or enquiry may appear, it becomes, 
in some measure, requisite to those, who would describe 
with success the obvious and outward appearances of life 
and manners. The anatomist presents to the eye the most 
hideous and disagreeable objects; but his science is useful 
to the painter in delineating even a Venus or an Helen. 
While the latter employs all the richest colours of his art, 
and gives his figures the most graceful and engaging airs; 
he must still carry his attention to the inward structure 
of the human body, the position of the muscles, the fabric 
of the bones, and the use and figure of every part or organ. 
Accuracy is, in every case, advantageous to beauty, and just 
reasoning to delicate sentiment. In vain would we exalt 
the one by depreciating the other. 

  Besides, we may observe, in every art or profession, even 
those which most concern life or action, that a spirit of 
accuracy, however acquired, carries all of them nearer their 
perfection, and renders them more subservient to the 
interests of society. And though a philosopher may live 
remote from business, the genius of philosophy, if carefully 
cultivated by several, must gradually diffuse itself through- 
out the whole society, and bestow a similar correctness on 
every art and calling. The politician will acquire greater 
foresight and subtility, in the subdividing and balancing 
of power; the lawyer more method and finer principles 
in his reasonings; and the general more regularity in his 
discipline, and more caution in his plans and operations. 
The stability of modern governments above the ancient, 
and the accuracy of modern philosophy, have improved, and 
probably will still improve, by similar gradations. 

  Were there no advantage to be reaped from these studies, 
beyond the gratification of an innocent curiosity, yet ought 
not even this to be despised; as being one accession to 
those few safe and harmless pleasures, which are bestowed 
on the human race. The sweetest and most inoffensive path 
of life leads through the avenues of science and learning; and 
whoever can either remove any obstructions in this way, 
or open up any new prospect, ought so far to be esteemed 
a benefactor to mankind. And though these researches 
may appear painful and fatiguing, it is with some minds 
as with some bodies, which being endowed with vigorous 
and florid health, require severe exercise, and reap a pleasure 
from what, to the generality of mankind, may seem burden- 
some and laborious. Obscurity, indeed, is painful to the 
mind as well as to the eye; but to bring light from 
obscurity, by whatever labour, must needs be delightful and 
rejoicing. 

  But this obscurity in the profound and abstract philos- 
ophy, is objected to, not only as painful and fatiguing, but 
as the inevitable source of uncertainty and error. Here in- 
deed lies the justest and most plausible objection against 
a considerable part of metaphysics, that they are not properly 
a science; but arise either from the fruitless efforts of 
human vanity, which would penetrate into subjects utterly 
inaccessible to the understanding, or from the craft of pop- 
ular superstitions, which, being unable to defend themselves 
on fair ground, raise these intangling brambles to cover and 
protect their weakness. Chased from the open country, these 
robbers fly into the forest, and lie in wait to break in upon 
every unguarded avenue of the mind, and overwhelm it 
with religious fears and prejudices. The stoutest antagonist, 
if he remit his watch a moment, is oppressed. And many, 
through cowardice and folly, open the gates to the enemies, 
and willingly receive them with reverence and submission, 
as their legal sovereigns. 

  But is this a sufficient reason, why philosophers should 
desist from such researches, and leave superstition still 
in possession of her retreat? Is it not proper to draw an 
opposite conclusion, and perceive the necessity of carrying 
the war into the most secret recesses of the enemy? In 
vain do we hope, that men, from frequent disappointment, 
will at last abandon such airy sciences, and discover the 
proper province of human reason. For, besides, that many 
persons find too sensible an interest in perpetually recalling 
such topics; besides this, I say, the motive of blind despair 
can never reasonably have place in the sciences; since, how- 
ever unsuccessful former attempts may have proved, there 
is still room to hope, that the industry, good fortune, or 
improved sagacity of succeeding generations may reach 
discoveries unknown to former ages. Each adventurous 
genius will still leap at the arduous prize, and find himself 
stimulated, rather than discouraged, by the failures of his 
predecessors; while he hopes that the glory of achieving 
so hard an adventure is reserved for him alone. The only 
method of freeing learning, at once, from these abstruse 
questions, is to enquire seriously into the nature of human 
understanding, and show, from an exact analysis of its 
powers and capacity, that it is by no means fitted for 
such remote and abstruse subjects. We must submit to 
this fatigue in order to live at ease ever after: and must 
cultivate true metaphysics with some care, in order to 
destroy the false and adulterate. Indolence, which, to some 
persons, affords a safeguard against this deceitful philos- 
ophy, is, with others, overbalanced by curiosity; and de- 
spair, which, at some moments, prevails, may give place after- 
wards to sanguine hopes and expectations. Accurate and 
just reasoning is the only catholic remedy, fitted for all 
persons and all dispositions; and is alone able to subvert 
that abstruse philosophy and metaphysical jargon, which 
being mixed up with popular superstition, renders it in 
a manner impenetrable to careless reasoners, and gives it 
the air of science and wisdom. 

  Besides this advantage of rejecting, after deliberate en- 
quiry, the most uncertain and disagreeable part of learning, 
there are many positive advantages, which result from an 
accurate scrutiny into the powers and faculties of human 
nature. It is remarkable concerning the operations of the 
mind, that, though most intimately present to us, yet, 
whenever they become the object of reflexion, they seem 
involved in obscurity; nor can the eye readily find those 
lines and boundaries, which discriminate and distinguish 
them. The objects are too fine to remain long in the same 
aspect or situation; and must be apprehended in an in- 
stant, by a superior penetration, derived from nature, and 
improved by habit and reflexion. It becomes, therefore, 
no inconsiderable part of science barely to know the different 
operations of the mind, to separate them from each other, to 
class them under their proper heads, and to correct all that 
seeming disorder, in which they lie involved, when made 
the object of reflexion and enquiry. This talk of ordering 
and distinguishing, which has no merit, when performed 
with regard to external bodies, the objects of our senses, 
rises in its value, when directed towards the operations 
of the mind, in proportion to the difficulty and labour, 
which we meet with in performing it. And if we can go no 
farther than this mental geography, or delineation of the 
distinct parts and powers of the mind, it is at least a satis- 
faction to go so far; and the more obvious this science 
may appear (and it is by no means obvious) the more con- 
temptible still must the ignorance of it be esteemed, in all 
pretenders to learning and philosophy. 

  Nor can there remain any suspicion, that this science 
is uncertain and chimerical; unless we should entertain 
such a scepticism as is entirely subversive of all speculation, 
and even action. It cannot be doubted, that the mind 
is endowed with several powers and faculties, that these 
powers are distinct from each other, that what is really 
distinct to the immediate perception may be distinguished 
by reflexion; and consequently, that there is a truth and 
falsehood in all propositions on this subject, and a truth 
and falsehood, which lie not beyond the compass of human 
understanding. There are many obvious distinctions of 
this kind, such as those between the will and understanding, 
the imagination and passions, which fall within the com- 
prehension of every human creature; and the finer and 
more philosophical distinctions are no less real and certain, 
though more difficult to be comprehended. Some instances, 
especially late ones, of success in these enquiries, may give 
us a juster notion of the certainty and solidity of this branch 
of learning. And shall we esteem it worthy the labour of 
a philosopher to give us a true system of the planets, and 
adjust the position and order of those remote bodies; 
while we affect to overlook those, who, with so much 
success, delineate the parts of the mind, in which we are so 
intimately concerned? 

  But may we not hope, that philosophy, cultivated with 
care, and encouraged by the attention of the public, may 
carry its researches still farther, and discover, at least in 
some degree, the secret springs and principles, by which the 
human mind is actuated in its operations? Astronomers 
had long contented themselves with proving, from the 
phaenomena, the true motions, order, and magnitude of 
the heavenly bodies: till a philosopher, at last, arose, 
who seems, from the happiest reasoning, to have also deter- 
mined the laws and forces, by which the revolutions of the 
planets are governed and directed. The like has been 
performed with regard to other parts of nature. And there 
is no reason to despair of equal success in our enquiries 
concerning the mental powers and economy, if prosecuted 
with equal capacity and caution. It is probable, that one 
operation and principle of the mind depends on another; 
which, again, may be resolved into one more general and 
universal: and how far these researches may possibly 
be carried, it will be difficult for us, before, or even after, 
a careful trial, exactly to determine. This is certain, that 
attempts of this kind are every day made even by those 
who philosophize the most negligently: and nothing can 
be more requisite than to enter upon the enterprize with 
thorough care and attention; that, if it lie within the 
compass of human understanding, it may at last be happily 
achieved; if not, it may, however, be rejected with some 
confidence and security. This last conclusion, surely, is not 
desirable; nor ought it to be embraced too rashly. For how 
much must we diminish from the beauty and value of this 
species of philosophy, upon such a supposition? Moralists 
have hitherto been accustomed, when they considered the 
vast multitude and diversity of those actions that excite 
our approbation or dislike, to search for some common 
principle, on which this variety of sentiments might depend. 
And though they have sometimes carried the matter too far, 
by their passion for some one general principle; it must, 
however, be confessed, that they are excusable in expecting 
to find some general principles, into which all the vices 
and virtues were justly to be resolved. The like has been 
the endeavour of critics, logicians, and even politicians: 
nor have their attempts been wholly unsuccessful; though 
perhaps longer time, greater accuracy, and more ardent 
application may bring these sciences still nearer their per- 
fection. To throw up at once all pretensions of this kind 
may justly be deemed more rash, precipitate, and dogmatical, 
than even the boldest and most affirmative philosophy, that 
has ever attempted to impose its crude dictates and prin- 
ciples on mankind. 

  What though these reasonings concerning human nature 
seem abstract, and of difficult comprehension? This affords 
no presumption of their falsehood. On the contrary, it 
seems impossible, that what has hitherto escaped so many 
wise and profound philosophers can be very obvious and 
easy. And whatever pains these researches may cost us, we 
may think ourselves sufficiently rewarded, not only in point 
of profit but of pleasure, if, by that means, we can make 
any addition to our stock of knowledge, in subjects of 
such unspeakable importance. 

  But as, after all, the abstractedness of these speculations 
is no recommendation, but rather a disadvantage to them, 
and as this difficulty may perhaps be surmounted by care 
and art, and the avoiding of all unnecessary detail, we have, 
in the following enquiry, attempted to throw some light 
upon subjects, from which uncertainty has hitherto deterred 
the wise, and obscurity the ignorant. Happy, if we can 
unite the boundaries of the different species of philosophy, 
by reconciling profound enquiry with clearness, and truth 
with novelty! And still more happy, if, reasoning in this 
easy manner, we can undermine the foundations of an 
abstruse philosophy, which seems to have hitherto served 
only as a shelter to superstition, and a cover to absurdity 
and error! 


SECTION II
OF THE ORIGIN OF IDEAS

  EVERY one will readily allow, that there is a consider- 
able difference between the perceptions of the mind, 
when a man feels the pain of excessive heat, or the 
pleasure of moderate warmth, and when he afterwards re- 
calls to his memory this sensation, or anticipates it by his 
imagination. These faculties may mimic or copy the percep- 
tions of the senses; but they never can entirely reach the 
force and vivacity of the original sentiment. The utmost we 
say of them, even when they operate with greatest vigour, is, 
that they represent their object in so lively a manner, that we 
could almost say we feel or see it: But, except the mind be 
disordered by disease or madness, they never can arrive 
at such a pitch of vivacity, as to render these perceptions 
altogether undistinguishable. All the colours of poetry, 
however splendid, can never paint natural objects in such 
a manner as to make the description be taken for a real 
landskip. The most lively thought is still inferior to the 
dullest sensation. 

  We may observe a like distinction to run through all the 
other perceptions of the mind. A man in a fit of anger, is 
actuated in a very different manner from one who only 
thinks of that emotion. If you tell me, that any person 
is in love, I easily understand your meaning, and from 
a just conception of his situation; but never can mistake 
that conception for the real disorders and agitations of the 
passion. When we reflect on our past sentiments and 
affections, our thought is a faithful mirror, and copies its 
objects truly; but the colours which it employs are faint 
and dull, in comparison of those in which our original per- 
ceptions were clothed. It requires no nice discernment or 
metaphysical head to mark the distinction between them. 

  Here therefore we may divide all the perceptions of the 
mind into two classes or species, which are distinguished 
by their different degrees of force and vivacity. The less 
forcible and lively are commonly denominated Thoughts or 
Ideas. The other species want a name in our language, 
and in most others; I suppose, because it was not requisite 
for any, but philosophical purposes, to rank them under 
a general term or appellation. Let us, therefore, use a little 
freedom, and call them Impressions; employing that word 
in a sense somewhat different from the usual. By the term 
impression, then, I mean all our more lively perceptions, 
when we hear, or see, or feel, or love, or hate, or desire, 
or will. And impressions are distinguished from ideas, 
which are the less lively perceptions, of which we are 
conscious, when we reflect on any of those sensations or 
movements above mentioned. 

  Nothing, at first view, may seem more unbounded than 
the thought of man, which not only escapes all human 
power and authority, but is not even restrained within the 
limits of nature and reality. To form monsters, and join 
incongruous shapes and appearances, costs the imagination 
no more trouble than to conceive the most natural and 
familiar objects. And while the body is confined to one 
planet, along which it creeps with pain and difficulty; the 
thought can in an instant transport us into the most dis- 
tant regions of the universe; or even beyond the universe, 
into the unbounded chaos, where nature is supposed to 
lie in total confusion. What never was seen, or heard 
of, may yet be conceived; nor is any thing beyond 
the power of thought, except what implies an absolute 
contradiction. 

  But though our thought seems to possess this unbounded 
liberty, we shall find, upon a nearer examination, that it is 
really confined within very narrow limits, and that all this 
creative power of the mind amounts to no more than 
the faculty of compounding, transposing, augmenting, or 
diminishing the materials afforded us by the senses and 
experience. When we think of a golden mountain, we 
only join two consistent ideas, gold, and mountain, with 
which we were formerly acquainted. A virtuous horse we 
can conceive; because, from our own feeling, we can 
conceive virtue; and this we may unite to the figure and 
shape of a horse, which is an animal familiar to us. In 
short, all the materials of thinking are derived either from 
our outward or inward sentiment: the mixture and com- 
position of these belongs alone to the mind and will. Or, 
to express myself in philosophical language, all our ideas or 
more feeble perceptions are copies of our impressions or 
more lively ones. 

  To prove this, the two following arguments will, I hope, 
be sufficient. First, when we analyze our thoughts or ideas, 
however compounded or sublime, we always find that they 
resolve themselves into such simple ideas as were copied 
from a precedent feeling or sentiment. Even those ideas, 
which, at first view, seem the most wide of this origin, are 
found, upon a nearer scrutiny, to be derived from it. The 
idea of God, as meaning an infinitely intelligent, wise, and 
good Being, arises from reflecting on the operations of our 
own mind, and augmenting, without limit, those qualities 
of goodness and wisdom. We may prosecute this enquiry 
to what length we please; where we shall always find, that 
every idea which we examine is copied from a similar 
impression. Those who would assert that this position is 
not universally true nor without exception, have only one, 
and that an easy method of refuting it; by producing that 
idea, which, in their opinion, is not derived from this source. 
It will then be incumbent on us, if we would maintain our 
doctrine, to produce the impression, or lively perception, 
which corresponds to it. 

  Secondly. If it happen, from a defect of the organ, 
that a man is not susceptible of any species of sensation, 
we always find that he is as little susceptible of the cor- 
respondent ideas. A blind man can form no notion of 
colours; a deaf man of sounds. Restore either of them 
that sense in which he is deficient; by opening this new 
inlet for his sensations, you also open an inlet for the ideas; 
and he finds no difficulty in conceiving these objects. The 
case is the same, if the object, proper for exciting any 
sensation, has never been applied to the organ. A Lap- 
lander or Negro has no notion of the relish of wine. 
And though there are few or no instances of a like 
deficiency in the mind, where a person has never felt or 
is wholly incapable of a sentiment or passion that belongs 
to his species; yet we find the same observation to take 
place in a less degree. A man of mild manners can form 
no idea of inveterate revenge or cruelty; nor can a selfish 
heart easily conceive the heights of friendship and gener- 
osity. It is readily allowed, that other beings may possess 
many senses of which we can have no conception; because 
the ideas of them have never been introduced to us in the 
only manner by which an idea can have access to the mind, 
to wit, by the actual feeling and sensation. 

  There is, however, one contradictory phenomenon, which 
may prove that it is not absolutely impossible for ideas 
to arise, independent of their correspondent impressions. 
I believe it will readily be allowed, that the several distinct 
ideas of colour, which enter by the eye, or those of sound, 
which are conveyed by the ear, are really different from 
each other; though, at the same time, resembling. Now 
if this be true of different colours, it must be no less so of 
the different shades of the same colour; and each shade 
produces a distinct idea, independent of the rest. For if 
this should be denied, it is possible, by the continual grada- 
tion of shades, to run a colour insensibly into what is most 
remote from it; and if you will not allow any of the means 
to be different, you cannot, without absurdity, deny the 
extremes to be the same. Suppose, therefore, a person 
to have enjoyed his sight for thirty years, and to have 
become perfectly acquainted with colours of all kinds 
except one particular shade of blue, for instance, which it 
never has been his fortune to meet with. Let all the 
different shades of that colour, except that single one, be 
placed before him, descending gradually from the deepest 
to the lightest; it is plain that he will perceive a blank, 
where that shade is wanting, and will be sensible that there 
is a greater distance in that place between the contiguous 
colour than in any other. Now I ask, whether it be 
possible for him, from his own imagination, to supply this 
deficiency, and raise up to himself the idea of that particular 
shade, though it had never been conveyed to him by his 
senses? I believe there are few but will be of opinion 
that he can: and this may serve as a proof that the simple 
ideas are not always, in every instance, derived from the 
correspondent impressions; though this instance is so 
singular, that it is scarcely worth our observing, and does 
not merit that for it alone we should alter our general 
maxim. 

  Here, therefore, is a proposition, which not only seems, 
in itself, simple and intelligible; but, if a proper use were 
made of it, might render every dispute equally intelligible, 
and banish all that jargon, which has so long taken 
possession of metaphysical reasonings, and drawn disgrace 
upon them. All ideas, especially abstract ones, are naturally 
faint and obscure: the mind has but a slender hold of them: 
they are apt to be confounded with other resembling ideas; 
and when we have often employed any term, though with- 
out a distinct meaning, we are apt to imagine it has a deter- 
minate idea annexed to it. On the contrary, all impressions, 
that is, all sensations, either outward or inward, are strong 
and vivid: the limits between them are more exactly deter- 
mined: nor is it easy to fall into any error or mistake with 
regard to them. When we entertain, therefore, any suspicion 
that a philosophical term is employed without any meaning 
or idea (as is but too frequent), we need but enquire, from 
what impression is that supposed idea derived? And if it 
be impossible to assign any, this will serve to confirm our 
suspicion. By bringing ideas into so clear a light we may 
reasonably hope to remove all dispute, which may arise, 
concerning their nature and reality.[1] 

[1] It is probable that no more was meant by these, who denied innate
ideas, than that all ideas were copies of our impressions; though it must
be confessed, that the terms, which they employed, were not chosen with
such caution, nor so exactly defined, as to prevent all mistakes about their
doctrine. For what is meant by innate? If innate be equivalent to natural,
then all the perceptions and ideas of the mind must be allowed to be innate
or natural, in whatever sense we take the latter word, whether in opposi-
tion to what is uncommon, artificial, or miraculous. If by innate be meant,
contemporary to our birth, the dispute seems to be frivolous; nor is it
worth while to enquire at what time thinking begins, whether before, at,
or after our birth. Again, the word idea, seems to be commonly taken in
a very loose sense, by LOCKE and others; as standing for any of our per-
ceptions, our sensations and passions, as well as thoughts. Now in this
sense, I should desire to know, what can be meant by asserting, that self-
love, or resentment of injuries, or the passion between the sexes is not innate?

But admitting these terms, impressions and ideas, in the sense above
explained, and understanding by innate, what is original or copied from
no precedent perception, then may we assert that all our impressions are
innate, and our ideas not innate.

To be ingenuous, I must own it to be my opinion, that LOCKE was
betrayed into this question by the schoolmen, who, making use of unde-
fined terms, draw out their disputes to a tedious length, without ever touch-
ing the point in question. A like ambiguity and circumlocution seem to run
through that philosopher's reasonings on this as well as most other subjects.


SECTION III
OF THE ASSOCIATION OF IDEAS

  IT IS evident that there is a principle of connexion be- 
tween the different thoughts or ideas of the mind, and 
that in their appearance to the memory or imagination, 
they introduce each other with a certain degree of method 
and regularity. In our more serious thinking or discourse 
this is so observable that any particular thought, which 
breaks in upon the regular tract or chain of ideas, is 
immediately remarked and rejected. And even in our 
wildest and most wandering reveries, nay in our very 
dreams, we shall find, if we reflect, that the imagination 
ran not altogether at adventures, but that there was still 
a connexion upheld among the different ideas, which suc- 
ceeded each other. Were the loosest and freest conversa- 
tion to be transcribed, there would immediately be observed 
something which connected it in all its transitions. Or 
where this is wanting, the person who broke the thread of 
discourse might still inform you, that there had secretly 
revolved in his mind a succession of thought, which had 
gradually led him from the subject of conversation. Among 
different languages, even where we cannot suspect the least 
connexion or communication, it is found, that the words, 
expressive of ideas, the most compounded, do yet nearly 
correspond to each other: a certain proof that the simple 
ideas, comprehended in the compound ones, were bound 
together by some universal principle, which had an equal 
influence on all mankind. 

  Though it be too obvious to escape observation, that 
different ideas are connected together; I do not find that 
any philosopher has attempted to enumerate or class all 
the principles of association; a subject, however, that seems 
worthy of curiosity. To me, there appear to be only three 
principles of connexion among ideas, namely, Resemblance, 
Contiguity in time or place, and Cause or Effect. 

  That these principles serve to connect ideas will not, I 
believe, be much doubted. A picture naturally leads our 
thoughts to the original:[1] the mention of one apartment 
in a building naturally introduces an enquiry or discourse 
concerning the others:[2] and if we think of a wound, we 
can scarcely forbear reflecting on the pain which follows it.[3] 
But that this enumeration is complete, and that there are 
no other principles of association except these, may be 
difficult to prove to the satisfaction of the reader, or even 
to a man's own satisfaction. All we can do, in such cases, 
is to run over several instances, and examine carefully the 
principle which binds the different thoughts to each other, 
never stopping till we render the principle as general as 
possible.[4] The more instances we examine, and the more 
care we employ, the more assurance shall we acquire, that 
the enumeration, which we form from the whole, is com- 
plete and entire. 

[1] Resemblance.

[2] Contiguity.

[3] Cause and effect.

[4] For instance, Contrast or Contrariety is also a connexion among Ideas:
but it may perhaps, be considered as a mixture of Causation and Resem-
blance. Where two objects are contrary, the one destroys the other; that
is, the cause of its annihilation, and the idea of the annihilation of an
object, implies the idea of its former existence.


SECTION IV
SCEPTICAL DOUBTS CONCERNING THE OPERATIONS OF 
THE UNDERSTANDING

PART I 

  ALL the objects of human reason or enquiry may 
naturally be divided into two kinds, to wit, Rela- 
tions of Ideas, and Matters of Fact. Of the first 
kind are the sciences of Geometry, Algebra, and Arithmetic; 
and in short, every affirmation which is either intuitively or 
demonstratively certain. That the square of the hypothenuse 
is equal to the square of the two sides, is a proposition 
which expresses a relation between these figures. That 
three times five is equal to the half of thirty, expresses a 
relation between these numbers. Propositions of this kind 
are discoverable by the mere operation of thought, without 
dependence on what is anywhere existent in the universe. 
Though there never were a circle or triangle in nature, the 
truths demonstrated by Euclid would for ever retain their 
certainty and evidence. 

  Matters of fact, which are the second objects of human 
reason, are not ascertained in the same manner; nor is our 
evidence of their truth, however great, of a like nature with 
the foregoing. The contrary of every matter of fact is still 
possible; because it can never imply a contradiction, and 
is conceived by the mind with the same facility and dis- 
tinctness, as if ever so conformable to reality. That the 
sun will not rise to-morrow is no less intelligible a propo- 
sition, and implies no more contradiction than the affirma- 
tion, that it will rise. We should in vain, therefore, attempt 
to demonstrate its falsehood. Were it demonstratively false, 
it would imply a contradiction, and could never be dis- 
tinctly conceived by the mind. 

  It may, therefore, be a subject worthy of curiosity, to 
enquire what is the nature of that evidence which assures 
us of any real existence and matter of fact, beyond the 
present testimony of our senses, or the records of our 
memory. This part of philosophy, it is observable, has been 
little cultivated, either by the ancients or moderns; and 
therefore our doubts and errors, in the prosecution of so 
important an enquiry, may be the more excusable; while 
we march through such difficult paths without any guide 
or direction. They may even prove useful, by exciting 
curiosity, and destroying that implicit faith and security, 
which is the bane of all reasoning and free enquiry. The 
discovery of defects in the common philosophy, if any such 
there be, will not, I presume, be a discouragement, but 
rather an incitement, as is usual, to attempt something 
more full and satisfactory than has yet been proposed to 
the public. 

  All reasonings concerning matter of fact seem to be 
founded on the relation of Cause and Effect. By means of 
that relation alone we can go beyond the evidence of our 
memory and senses. If you were to ask a man, why he 
believes any matter of fact, which is absent; for instance, 
that his friend is in the country, or in France; he would 
give you a reason; and this reason would be some other 
fact; as a letter received from him, or the knowledge of his 
former resolutions and promises. A man finding a watch 
or any other machine in a desert island, would conclude 
that there had once been men in that island. All our rea- 
sonings concerning fact are of the same nature. And here 
it is constantly 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 pres- 
ence 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 a priori; 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. 
Adam, 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 suffo- 
cate 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 pro- 
duced it, or the effects which will arise from it; nor can 
our reason, unassisted by experience, ever draw any in- 
ference concerning real existence and matter of fact. 

  This proposition, that causes and effects are discoverable, 
not by reason but by experience, 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 load- 
stone, could ever be discovered by arguments a priori. 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 tiger? 

  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 pro- 
nounce 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, suf- 
fice. 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 
anything 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 a priori, is there anything 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 con- 
sult 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 dif- 
ferent 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 con- 
sistent and conceivable. Why then should we give the 
preference to one, which is no more consistent or conceivable 
than the rest? All our reasonings a priori 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, a priori, must be 
entirely arbitrary. And even after it is suggested, the con- 
junction 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, there- 
fore, should we pretend to determine any single event, or 
infer any cause or effect, without the assistance of observa- 
tion 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 
distinctly the action of that power, which produces any 
single effect in the universe. It is confessed, that the 
utm