A Treatise concening the Principles of  human knowledge wherein

the chief causes of errors and difficulty in the sciences, with the

grounds of scepticism, atheism, and irreligion, are inquired into.

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1. It is evident to any one who takes a survey of the objects of
human knowledge, that they are either ideas actually imprinted on
the senses; or else such as are perceived by attending to the passions
and operations of the mind; or lastly, ideas formed by help of
memory and imagination- either compounding, dividing, or barely
representing those originally perceived in the aforesaid ways. By
sight I have the ideas of light and colours, with their several
degrees and variations. By touch I perceive hard and soft, heat and
cold, motion and resistance, and of all these more and less either
as to quantity or degree. Smelling furnishes me with odours; the
palate with tastes; and hearing conveys sounds to the mind in all
their variety of tone and composition. And as several of these are
observed to accompany each other, they come to be marked by one
name, and so to be reputed as one thing. Thus, for example a certain
colour, taste, smell, figure and consistence having been observed to
go together, are accounted one distinct thing, signified by the name
apple; other collections of ideas constitute a stone, a tree, a
book, and the like sensible things- which as they are pleasing or
disagreeable excite the passions of love, hatred, joy, grief, and so
forth.
  2. But, besides all that endless variety of ideas or objects of
knowledge, there is likewise something which knows or perceives
them, and exercises divers operations, as willing, imagining,
remembering, about them. This perceiving, active being is what I
call mind, spirit, soul, or myself. By which words I do not denote any
one of my ideas, but a thing entirely distinct from them, wherein,
they exist, or, which is the same thing, whereby they are perceived-
for the existence of an idea consists in being perceived.
  3. That neither our thoughts, nor passions, nor ideas formed by
the imagination, exist without the mind, is what everybody will allow.
And it seems no less evident that the various sensations or ideas
imprinted on the sense, however blended or combined together (that is,
whatever objects they compose), cannot exist otherwise than in a
mind perceiving them.- I think an intuitive knowledge may be
obtained of this by any one that shall attend to what is meant by
the term exists, when applied to sensible things. The table I write on
I say exists, that is, I see and feel it; and if I were out of my
study I should say it existed- meaning thereby that if I was in my
study I might perceive it, or that some other spirit actually does
perceive it. There was an odour, that is, it was smelt; there was a
sound, that is, it was heard; a colour or figure, and it was perceived
by sight or touch. This is all that I can understand by these and
the like expressions. For as to what is said of the absolute existence
of unthinking things without any relation to their being perceived,
that seems perfectly unintelligible. Their esse is percepi, nor is
it possible they should have any existence out of the minds or
thinking things which perceive them.
  4. It is indeed an opinion strangely prevailing amongst men, that
houses, mountains, rivers, and in a word all sensible objects, have an
existence, natural or real, distinct from their being perceived by the
understanding. But, with how great an assurance and acquiescence
soever this principle may be entertained in the world, yet whoever
shall find in his heart to call it in question may, if I mistake
not, perceive it to involve a manifest contradiction. For, what are
the fore-mentioned objects but the things we perceive by sense? and
what do we perceive besides our own ideas or sensations? and is it not
plainly repugnant that any one of these, or any combination of them,
should exist unperceived?
  5. If we thoroughly examine this tenet it will, perhaps, be found at
bottom to depend on the doctrine of abstract ideas. For can there be a
nicer strain of abstraction than to distinguish the existence of
sensible objects from their being perceived, so as to conceive them
existing unperceived? Light and colours, heat and cold, extension
and figures- in a word the things we see and feel- what are they but
so many sensations, notions, ideas, or impressions on the sense? and
is it possible to separate, even in thought, any of these from
perception? For my part, I might as easily divide a thing from itself.
I may, indeed, divide in my thoughts, or conceive apart from each
other, those things which, perhaps I never perceived by sense so
divided. Thus, I imagine the trunk of a human body without the
limbs, or conceive the smell of a rose without thinking on the rose
itself. So far, I will not deny, I can abstract- if that may
properly be called abstraction which extends only to the conceiving
separately such objects as it is possible may really exist or be
actually perceived asunder. But my conceiving or imagining power
does not extend beyond the possibility of real existence or
perception. Hence, as it is impossible for me to see or feel
anything without an actual sensation of that thing, so is it
impossible for me to conceive in my thoughts any sensible thing or
object distinct from the sensation or perception of it.
  6. Some truths there are so near and obvious to the mind that a
man need only open his eyes to see them. Such I take this important
one to be, viz., that all the choir of heaven and furniture of the
earth, in a word all those bodies which compose the mighty frame of
the world, have not any subsistence without a mind, that their being
is to be perceived or known; that consequently so long as they are not
actually perceived by me, or do not exist in my mind or that of any
other created spirit, they must either have no existence at all, or
else subsist in the mind of some Eternal Spirit- it being perfectly
unintelligible, and involving all the absurdity of abstraction, to
attribute to any single part of them an existence independent of a
spirit. To be convinced of which, the reader need only reflect, and
try to separate in his own thoughts the being of a sensible thing from
its being perceived.
  7. From what has been said it follows there is not any other
Substance than Spirit, or that which perceives. But, for the fuller
proof of this point, let it be considered the sensible qualities are
colour, figure, motion, smell, taste, etc., i.e. the ideas perceived
by sense. Now, for an idea to exist in an unperceiving thing is a
manifest contradiction, for to have an idea is all one as to perceive;
that therefore wherein colour, figure, and the like qualities exist
must perceive them; hence it is clear there can be no unthinking
substance or substratum of those ideas.
  8. But, say you, though the ideas themselves do not exist without
the mind, yet there may be things like them, whereof they are copies
or resemblances, which things exist without the mind in an
unthinking substance. I answer, an idea can be like nothing but an
idea; a colour or figure can be like nothing but another colour or
figure. If we look but never so little into our thoughts, we shall
find it impossible for us to conceive a likeness except only between
our ideas. Again, I ask whether those supposed originals or external
things, of which our ideas are the pictures or representations, be
themselves perceivable or no? If they are, then they are ideas and
we have gained our point; but if you say they are not, I appeal to any
one whether it be sense to assert a colour is like something which
is invisible; hard or soft, like something which is intangible; and so
of the rest.
  9. Some there are who make a distinction betwixt primary and
secondary qualities. By the former they mean extension, figure,
motion, rest, solidity or impenetrability, and number; by the latter
they denote all other sensible qualities, as colours, sounds,
tastes, and so forth. The ideas we have of these they acknowledge
not to be the resemblances of anything existing without the mind, or
unperceived, but they will have our ideas of the primary qualities
to be patterns or images of things which exist without the mind, in an
unthinking substance which they call Matter. By Matter, therefore,
we are to understand an inert, senseless substance, in which
extension, figure, and motion do actually subsist. But it is evident
from what we have already shown, that extension, figure, and motion
are only ideas existing in the mind, and that an idea can be like
nothing but another idea, and that consequently neither they nor their
archetypes can exist in an unperceiving substance. Hence, it is
plain that that the very notion of what is called Matter or
corporeal substance, involves a contradiction in it.

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72. If we follow the light of reason, we shall, from the constant
uniform method of our sensations, collect the goodness and wisdom of
the Spirit who excites them in our minds; but this is all that I can
see reasonably concluded from thence. To me, I say, it is evident that
the being of a spirit infinitely wise, good, and powerful is
abundantly sufficient to explain all the appearances of nature. But,
as for inert, senseless Matter, nothing that I perceive has any the
least connexion with it, or leads to the thoughts of it. And I would
fain see any one explain any the meanest phenomenon in nature by it,
or shew any manner of reason, though in the lowest rank of
probability, that he can have for its existence, or even make any
tolerable sense or meaning of that supposition. For, as to its being
an occasion, we have, I think, evidently shewn that with regard to
us it is no occasion. It remains therefore that it must be, if at all,
the occasion to God of exciting ideas in us; and what this amounts
to we have just now seen.

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110. The best key for the aforesaid analogy or natural Science
will be easily acknowledged to be a certain celebrated Treatise of
Mechanics. In the entrance of which justly admired treatise, Time,
Space, and Motion are distinguished into absolute and relative, true
and apparent, mathematical and vulgar; which distinction, as it is
at large explained by the author, does suppose these quantities to
have an existence without the mind; and that they are ordinarily
conceived with relation to sensible things, to which nevertheless in
their own nature they bear no relation at all.
  111. As for Time, as it is there taken in an absolute or
abstracted sense, for the duration or perseverance of the existence of
things, I have nothing more to add concerning it after what has been
already said on that subject. Sect. 97 and 98. For the rest, this
celebrated author holds there is an absolute Space, which, being
unperceivable to sense, remains in itself similar and immovable; and
relative space to be the measure thereof, which, being movable and
defined by its situation in respect of sensible bodies, is vulgarly
taken for immovable space. Place he defines to be that part of space
which is occupied by any body; and according as the space is
absolute or relative so also is the place. Absolute Motion is said
to be the translation of a body from absolute place to absolute place,
as relative motion is from one relative place to another. And, because
the parts of absolute space do not fall under our senses, instead of
them we are obliged to use their sensible measures, and so define both
place and motion with respect to bodies which we regard as
immovable. But, it is said in philosophical matters we must abstract
from our senses, since it may be that none of those bodies which
seem to be quiescent are truly so, and the same thing which is moved
relatively may be really at rest; as likewise one and the same body
may be in relative rest and motion, or even moved with contrary
relative motions at the same time, according as its place is variously
defined. All which ambiguity is to be found in the apparent motions,
but not at all in the true or absolute, which should therefore be
alone regarded in philosophy. And the true as we are told are
distinguished from apparent or relative motions by the following
properties.- First, in true or absolute motion all parts which
preserve the same position with respect of the whole, partake of the
motions of the whole. Secondly, the place being moved, that which is
placed therein is also moved; so that a body moving in a place which
is in motion doth participate the motion of its place. Thirdly, true
motion is never generated or changed otherwise than by force impressed
on the body itself. Fourthly, true motion is always changed by force
impressed on the body moved. Fifthly, in circular motion barely
relative there is no centrifugal force, which, nevertheless, in that
which is true or absolute, is proportional to the quantity of motion.
  112. But, notwithstanding what has been said, I must confess it does
not appear to me that there can be any motion other than relative;
so that to conceive motion there must be at least conceived two
bodies, whereof the distance or position in regard to each other is
varied. Hence, if there was one only body in being it could not
possibly be moved. This seems evident, in that the idea I have of
motion doth necessarily include relation.
  113. But, though in every motion it be necessary to conceive more
bodies than one, yet it may be that one only is moved, namely, that on
which the force causing the change in the distance or situation of the
bodies, is impressed. For, however some may define relative motion, so
as to term that body moved which changes its distance from some
other body, whether the force or action causing that change were
impressed on it or no, yet as relative motion is that which is
perceived by sense, and regarded in the ordinary affairs of life, it
should seem that every man of common sense knows what it is as well as
the best philosopher. Now, I ask any one whether, in his sense of
motion as he walks along the streets, the stones he passes over may be
said to move, because they change distance with his feet? To me it
appears that though motion includes a relation of one thing to
another, yet it is not necessary that each term of the relation be
denominated from it. As a man may think of somewhat which does not
think, so a body may be moved to or from another body which is not
therefore itself in motion.
  114. As the place happens to be variously defined, the motion
which is related to it varies. A man in a ship may be said to be
quiescent with relation to the sides of the vessel, and yet move
with relation to the land. Or he may move eastward in respect of the
one, and westward in respect of the other. In the common affairs of
life men never go beyond the earth to define the place of any body;
and what is quiescent in respect of that is accounted absolutely to be
so. But philosophers, who have a greater extent of thought, and juster
notions of the system of things, discover even the earth itself to
be moved. In order therefore to fix their notions they seem to
conceive the corporeal world as finite, and the utmost unmoved walls
or shell thereof to be the place whereby they estimate true motions.
If we sound our own conceptions, I believe we may find all the
absolute motion we can frame an idea of to be at bottom no other
than relative motion thus defined. For, as hath been already observed,
absolute motion, exclusive of all external relation, is
incomprehensible; and to this kind of relative motion all the
above-mentioned properties, causes, and effects ascribed to absolute
motion will, if I mistake not, be found to agree. As to what is said
of the centrifugal force, that it does not at all belong to circular
relative motion, I do not see how this follows from the experiment
which is brought to prove it. See Philosophiae Naturalis Principia
Mathematica, in Schol. Def. VIII. For the water in the vessel at
that time wherein it is said to have the greatest relative circular
motion, hath, I think, no motion at all; as is plain from the
foregoing section.
  115. For, to denominate a body moved it is requisite, first, that it
change its distance or situation with regard to some other body; and
secondly, that the force occasioning that change be applied to it.
If either of these be wanting, I do not think that, agreeably to the
sense of mankind, or the propriety of language, a body can be said
to be in motion. I grant indeed that it is possible for us to think
a body which we see change its distance from some other to be moved,
though it have no force applied to it (in which sense there may be
apparent motion), but then it is because the force causing the
change of distance is imagined by us to be applied or impressed on
that body thought to move; which indeed shews we are capable of
mistaking a thing to be in motion which is not, and that is all.
  116. From what has been said it follows that the philosophic
consideration of motion does not imply the being of an absolute Space,
distinct from that which is perceived by sense and related bodies;
which that it cannot exist without the mind is clear upon the same
principles that demonstrate the like of all other objects of sense.
And perhaps, if we inquire narrowly, we shall find we cannot even
frame an idea of pure Space exclusive of all body. This I must confess
seems impossible, as being a most abstract idea. When I excite a
motion in some part of my body, if it be free or without resistance, I
say there is Space; but if I find a resistance, then I say there is
Body; and in proportion as the resistance to motion is lesser or
greater, I say the space is more or less pure. So that when I speak of
pure or empty space, it is not to be supposed that the word "space"
stands for an idea distinct from or conceivable without body and
motion- though indeed we are apt to think every noun substantive
stands for a distinct idea that may be separated from all others;
which has occasioned infinite mistakes. When, therefore, supposing all
the world to be annihilated besides my own body, I say there still
remains pure Space, thereby nothing else is meant but only that I
conceive it possible for the limbs of my body to be moved on all sides
without the least resistance, but if that, too, were annihilated
then there could be no motion, and consequently no Space. Some,
perhaps, may think the sense of seeing doth furnish them with the idea
of pure space; but it is plain from what we have elsewhere shewn, that
the ideas of space and distance are not obtained by that sense. See
the Essay concerning Vision.
  117. What is here laid down seems to put an end to all those
disputes and difficulties that have sprung up amongst the learned
concerning the nature of pure Space. But the chief advantage arising
from it is that we are freed from that dangerous dilemma, to which
several who have employed their thoughts on that subject imagine
themselves reduced, to wit, of thinking either that Real Space is God,
or else that there is something beside God which is eternal,
uncreated, infinite, indivisible, immutable. Both which may justly
be thought pernicious and absurd notions. It is certain that not a few
divines, as well as philosophers of great note, have, from the
difficulty they found in conceiving either limits or annihilation of
space, concluded it must be divine. And some of late have set
themselves particularly to shew the incommunicable attributes of God
agree to it. Which doctrine, how unworthy soever it may seem of the
Divine Nature, yet I do not see how we can get clear of it, so long as
we adhere to the received opinions.

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145. From what has been said, it is plain that we cannot know the
existence of other spirits otherwise than by their operations, or
the ideas by them excited in us. I perceive several motions,
changes, and combinations of ideas, that inform me there are certain
particular agents, like myself, which accompany them and concur in
their production. Hence, the knowledge I have of other spirits is
not immediate, as is the knowledge of my ideas; but depending on the
intervention of ideas, by me referred to agents or spirits distinct
from myself, as effects or concomitant signs.
  146. But, though there be some things which convince us human agents
are concerned in producing them; yet it is evident to every one that
those things which are called the Works of Nature, that is, the far
greater part of the ideas or sensations perceived by us, are not
produced by, or dependent on, the wills of men. There is therefore
some other Spirit that causes them; since it is repugnant that they
should subsist by themselves. See sect. 29. 
[Here is sec. 29: But, whatever power I may have over my own thoughts, I find
the ideas actually perceived by Sense have not a like dependence on my
will. When in broad daylight I open my eyes, it is not in my power
to choose whether I shall see or no, or to determine what particular
objects shall present themselves to my view; and so likewise as to the
hearing and other senses; the ideas imprinted on them are not
creatures of my will.] 
There is therefore some other Will or Spirit
that produces them. But, if we attentively
consider the constant regularity, order, and concatenation of
natural things, the surprising magnificence, beauty, and perfection of
the larger, and the exquisite contrivance of the smaller parts of
creation, together with the exact harmony and correspondence of the
whole, but above all the never-enough-admired laws of pain and
pleasure, and the instincts or natural inclinations, appetites, and
passions of animals; I say if we consider all these things, and at the
same time attend to the meaning and import of the attributes One,
Eternal, Infinitely Wise, Good, and Perfect, we shall clearly perceive
that they belong to the aforesaid Spirit, "who works all in all,"
and "by whom all things consist."
  147. Hence, it is evident that God is known as certainly and
immediately as any other mind or spirit whatsoever distinct from
ourselves. We may even assert that the existence of God is far more
evidently perceived than the existence of men; because the effects
of nature are infinitely more numerous and considerable than those
ascribed to human agents. There is not any one mark that denotes a
man, or effect produced by him, which does not more strongly evince
the being of that Spirit who is the Author of Nature. For, it is
evident that in affecting other persons the will of man has no other
object than barely the motion of the limbs of his body; but that
such a motion should be attended by, or excite any idea in the mind of
another, depends wholly on the will of the Creator. He alone it is
who, "upholding all things by the word of His power," maintains that
intercourse between spirits whereby they are able to perceive the
existence of each other. And yet this pure and clear light which
enlightens every one is itself invisible.
  148. It seems to be a general pretence of the unthinking herd that
they cannot see God. Could we but see Him, say they, as we see a
man, we should believe that He is, and believing obey His commands.
But alas, we need only open our eyes to see the Sovereign Lord of
all things, with a more full and clear view than we do any one of
our fellow-creatures. Not that I imagine we see God (as some will have
it) by a direct and immediate view; or see corporeal things, not by
themselves, but by seeing that which represents them in the essence of
God, which doctrine is, I must confess, to me incomprehensible. But
I shall explain my meaning;- A human spirit or person is not perceived
by sense, as not being an idea; when therefore we see the colour,
size, figure, and motions of a man, we perceive only certain
sensations or ideas excited in our own minds; and these being
exhibited to our view in sundry distinct collections, serve to mark
out unto us the existence of finite and created spirits like
ourselves. Hence it is plain we do not see a man- if by man is meant
that which lives, moves, perceives, and thinks as we do- but only such
a certain collection of ideas as directs us to think there is a
distinct principle of thought and motion, like to ourselves,
accompanying and represented by it. And after the same manner we see
God; all the difference is that, whereas some one finite and narrow
assemblage of ideas denotes a particular human mind, whithersoever
we direct our view, we do at all times and in all places perceive
manifest tokens of the Divinity: everything we see, hear, feel, or
anywise perceive by sense, being a sign or effect of the power of God;
as is our perception of those very motions which are produced by men.
  149. It is therefore plain that nothing can be more evident to any
one that is capable of the least reflexion than the existence of
God, or a Spirit who is intimately present to our minds, producing
in them all that variety of ideas or sensations which continually
affect us, on whom we have an absolute and entire dependence, in short
"in whom we live, and move, and have our being." That the discovery of
this great truth, which lies so near and obvious to the mind, should
be attained to by the reason of so very few, is a sad instance of
the stupidity and inattention of men, who, though they are
surrounded with such clear manifestations of the Deity, are yet so
little affected by them that they seem, as it were, blinded with
excess of light.