1. Knowledge of the existence of other finite beings is to be had only by actual sensation. The
knowledge of our own being we have by intuition. The existence of a God, reason clearly makes
known to us, as has been shown.
The knowledge of the existence of any other thing we can have only by sensation: for there being no
necessary connexion of real existence with any idea a man hath in his memory; nor of any other
existence but that of God with the existence of any particular man: no particular man can know the
existence of any other being, but only when, by actual operating upon him, it makes itself perceived
by him. For, the having the idea of anything in our mind, no more proves the existence of that thing,
than the picture of a man evidences his being in the world, or the visions of a dream make thereby a
true history.
2. Instance: whiteness of this paper. It is therefore the actual receiving of ideas from without that
gives us notice of the existence of other things, and makes us know, that something doth exist at
that time without us, which causes that idea in us; though perhaps we neither know nor consider
how it does it. For it takes not from the certainty of our senses, and the ideas we receive by them,
that we know not the manner wherein they are produced: v.g. whilst I write this, I have, by the paper
affecting my eyes, that idea produced in my mind, which, whatever object causes, I call white; by
which I know that that quality or accident (i.e., whose appearance before my eyes always causes
that idea) doth really exist, and hath a being without me. And of this, the greatest assurance I can
possibly have, and to which my faculties can attain, is the testimony of my eyes, which are the
proper and sole judges of this thing; whose testimony I have reason to rely on as so certain, that I
can no more doubt, whilst I write this, that I see white and black, and that something really exists
that causes that sensation in me, than that I write or move my hand; which is a certainty as great as
human nature is capable of, concerning the existence of anything, but a man's self alone, and of
God.
3. This notice by our senses, though not so certain as demonstration, yet may be called knowledge,
and proves the existence of things without us. The notice we have by our senses of the existing of
things without us, though it be not altogether so certain as our intuitive knowledge, or the deductions
of our reason employed about the clear abstract ideas of our own minds; yet it is an assurance that
deserves the name of knowledge. If we persuade ourselves that our faculties act and inform us right
concerning the existence of those objects that affect them, it cannot pass for an ill-grounded
confidence: for I think nobody can, in earnest, be so sceptical as to be uncertain of the existence of
those things which he sees and feels. At least, he that can doubt so far, (whatever he may have with
his own thoughts,) will never have any controversy with me; since he can never be sure I say
anything contrary to his own opinion. As to myself, I think God has given me assurance enough of
the existence of things without me: since, by their different application, I can produce in myself both
pleasure and pain, which is one great concernment of my present state. This is certain: the
confidence that our faculties do not herein deceive us, is the greatest assurance we are capable of
concerning the existence of material beings. For we cannot act anything but by our faculties; nor talk
of knowledge itself, but by the help of those faculties which are fitted to apprehend even what
knowledge is.
But besides the assurance we have from our senses themselves, that they do not err in the
information they give us of the existence of things without us, when they are affected by them, we
are further confirmed in this assurance by other concurrent reasons:--
4. I. Confirmed by concurrent reasons:--First, because we cannot have ideas of sensation but by the
inlet of the senses. It is plain those perceptions are produced in us by exterior causes affecting our
senses: because those that want the organs of any sense, never can have the ideas belonging to
that sense produced in their minds. This is too evident to be doubted: and therefore we cannot but
be assured that they come in by the organs of that sense, and no other way. The organs
themselves, it is plain, do not produce them: for then the eyes of a man in the dark would produce
colours, and his nose smell roses in the winter: but we see nobody gets the relish of a pineapple, till
he goes to the Indies, where it is, and tastes it.
5. II. Secondly, Because we find that an idea from actual sensation, and another from memory, are
very distinct perceptions. Because sometimes I find that I cannot avoid the having those ideas
produced in my mind. For though, when my eyes are shut, or windows fast, I can at pleasure recall
to my mind the ideas of light, or the sun, which former sensations had lodged in my memory; so I
can at pleasure lay by that idea, and take into my view that of the smell of a rose, or taste of sugar.
But, if I turn my eyes at noon towards the sun, I cannot avoid the ideas which the light or sun then
produces in me. So that there is a manifest difference between the ideas laid up in my memory,
(over which, if they were there only, I should have constantly the same power to dispose of them,
and lay them by at pleasure,) and those which force themselves upon me, and I cannot avoid
having. And therefore it must needs be some exterior cause, and the brisk acting of some objects
without me, whose efficacy I cannot resist, that produces those ideas in my mind, whether I will or
no. Besides, there is nobody who doth not perceive the difference in himself between contemplating
the sun, as he hath the idea of it in his memory, and actually looking upon it: of which two, his
perception is so distinct, that few of his ideas are more distinguishable one from another. And
therefore he hath certain knowledge that they are not both memory, or the actions of his mind, and
fancies only within him; but that actual seeing hath a cause without.
6. III. Thirdly, because pleasure or pain, which accompanies actual sensation, accompanies not the
returning of those ideas without the external objects. Add to this, that many of those ideas are
produced in us with pain, which afterwards we remember without the least offence. Thus, the pain of
heat or cold, when the idea of it is revived in our minds, gives us no disturbance; which, when felt,
was very troublesome; and is again, when actually repeated: which is occasioned by the disorder
the external object causes in our bodies when applied to them: and we remember the pains of
hunger, thirst, or the headache, without any pain at all; which would either never disturb us, or else
constantly do it, as often as we thought of it, were there nothing more but ideas floating in our
minds, and appearances entertaining our fancies, without the real existence of things affecting us
from abroad. The same may be said of pleasure, accompanying several actual sensations. And
though mathematical demonstration depends not upon sense, yet the examining them by diagrams
gives great credit to the evidence of our sight, and seems to give it a certainty approaching to that of
demonstration itself. For, it would be very strange, that a man should allow it for an undeniable truth,
that two angles of a figure, which he measures by lines and angles of a diagram, should be bigger
one than the other, and yet doubt of the existence of those lines and angles, which by looking on he
makes use of to measure that by.
7. IV. Fourthly, because our senses assist one another's testimony of the existence of outward
things, and enable us to predict. Our senses in many cases bear witness to the truth of each other's
report, concerning the existence of sensible things without us. He that sees a fire, may, if he doubt
whether it be anything more than a bare fancy, feel it too; and be convinced, by putting his hand in it.
Which certainly could never be put into such exquisite pain by a bare idea or phantom, unless that
the pain be a fancy too: which yet he cannot, when the burn is well, by raising the idea of it, bring
upon himself again.
Thus I see, whilst I write this, I can change the appearance of the paper; and by designing the
letters, tell beforehand what new idea it shall exhibit the very next moment, by barely drawing my
pen over it: which will neither appear (let me fancy as much as I will) if my hands stand still; or
though I move my pen, if my eyes be shut: nor, when those characters are once made on the paper,
can I choose afterwards but see them as they are; that is, have the ideas of such letters as I have
made. Whence it is manifest, that they are not barely the sport and play of my own imagination,
when I find that the characters that were made at the pleasure of my own thoughts, do not obey
them; nor yet cease to be, whenever I shall fancy it, but continue to affect my senses constantly and
regularly, according to the figures I made them. To which if we will add, that the sight of those shall,
from another man, draw such sounds as I beforehand design they shall stand for, there will be little
reason left to doubt that those words I write do really exist without me, when they cause a long
series of regular sounds to affect my ears, which could not be the effect of my imagination, nor
could my memory retain them in that order.
8. This certainty is as great as our condition needs. But yet, if after all this any one will be so
sceptical as to distrust his senses, and to affirm that all we see and hear, feel and taste, think and
do, during our whole being, is but the series and deluding appearances of a long dream, whereof
there is no reality; and therefore will question the existence of all things, or our knowledge of
anything: I must desire him to consider, that, if all be a dream, then he doth but dream that he
makes the question, and so it is not much matter that a waking man should answer him. But yet, if
he pleases, he may dream that I make him this answer, That the certainty of things existing in rerum
natura when we have the testimony of our senses for it is not only as great as our frame can attain
to, but as our condition needs. For, our faculties being suited not to the full extent of being, nor to a
perfect, clear, comprehensive knowledge of things free from all doubt and scruple; but to the
preservation of us, in whom they are; and accommodated to the use of life: they serve to our
purpose wen enough, if they will but give us certain notice of those things, which are convenient or
inconvenient to us. For he that sees a candle burning, and hath experimented the force of its flame
by putting his finger in it, will little doubt that this is something existing without him, which does him
harm, and puts him to great pain; which is assurance enough, when no man requires greater
certainty to govern his actions by than what is as certain as his actions themselves. And if our
dreamer pleases to try whether the glowing heat of a glass furnace be barely a wandering
imagination in a drowsy man's fancy, by putting his hand into it, he may perhaps be wakened into a
certainty greater than he could wish, that it is something more than bare imagination. So that this
evidence is as great as we can desire, being as certain to us as our pleasure or pain, i.e., happiness
or misery; beyond which we have no concernment, either of knowing or being. Such an assurance
of the existence of things without us is sufficient to direct us in the attaining the good and avoiding
the evil which is caused by them, which is the important concernment we have of being made
acquainted with them.
9. But reaches no further than actual sensation. In fine, then, when our senses do actually convey
into our understandings any idea, we cannot but be satisfied that there doth something at that time
really exist without us, which doth affect our senses, and by them give notice of itself to our
apprehensive faculties, and actually produce that idea which we then perceive: and we cannot so far
distrust their testimony, as to doubt that such collections of simple ideas as we have observed by
our senses to be united together, do really exist together. But this knowledge extends as far as the
present testimony of our senses, employed about particular objects that do then affect them, and no
further. For if I saw such a collection of simple ideas as is wont to be called man, existing together
one minute since, and am now alone, I cannot be certain that the same man exists now, since there
is no necessary connexion of his existence a minute since with his existence now: by a thousand
ways he may cease to be, since I had the testimony of my senses for his existence. And if I cannot
be certain that the man I saw last to-day is now in being, I can less be certain that he is so who hath
been longer removed from my senses, and I have not seen since yesterday, or since the last year:
and much less can I be certain of the existence of men that I never saw. And, therefore, though it be
highly probable that millions of men do now exist, yet, whilst I am alone, writing this, I have not that
certainty of it which we strictly call knowledge; though the great likelihood of it puts me past doubt,
and it be reasonable for me to do several things upon the confidence that there are men (and men
also of my acquaintance, with whom I have to do) now in the world: but this is but probability, not
knowledge.
10. Folly to expect demonstration in everything. Whereby yet we may observe how foolish and vain
a thing it is for a man of a narrow knowledge, who having reason given him to judge of the different
evidence and probability of things, and to be swayed accordingly; how vain, I say, it is to expect
demonstration and certainty in things not capable of it; and refuse assent to very rational
propositions, and act contrary to very plain and clear truths, because they cannot be made out so
evident, as to surmount every the least (I will not say reason, but) pretence of doubting. He that, in
the ordinary affairs of life, would admit of nothing but direct plain demonstration, would be sure of
nothing in this world, but of perishing quickly. The wholesomeness of his meat or drink would not
give him reason to venture on it: and I would fain know what it is he could do upon such grounds as
are capable of no doubt, no objection.
11. Past existence of other things is known by memory. As when our senses are actually employed
about any object, we do know that it does exist; so by our memory we may be assured, that
heretofore things that affected our senses have existed. And thus we have knowledge of the past
existence of several things, whereof our senses having informed us, our memories still retain the
ideas; and of this we are past all doubt, so long as we remember well. But this knowledge also
reaches no further than our senses have formerly assured us. Thus, seeing water at this instant, it is
an unquestionable truth to me that water doth exist: and remembering that I saw it yesterday, it will
also be always true, and as long as my memory retains it always an undoubted proposition to me,
that water did exist the 10th of July, 1688; as it will also be equally true that a certain number of very
fine colours did exist, which at the same time I saw upon a bubble of that water: but, being now quite
out of sight both of the water and bubbles too, it is no more certainly known to me that the water
doth now exist, than that the bubbles or colours therein do so: it being no more necessary that water
should exist to-day, because it existed yesterday, than that the colours or bubbles exist to-day,
because they existed yesterday, though it be exceedingly much more probable; because water hath
been observed to continue long in existence, but bubbles, and the colours on them, quickly cease to
be.
12. The existence of other finite spirits not knowable, and rests on faith. What ideas we have of
spirits, and how we come by them, I have already shown. But though we have those ideas in our
minds, and know we have them there, the having the ideas of spirits does not make us know that
any such things do exist without us, or that there are any finite spirits, or any other spiritual beings,
but the Eternal God. We have ground from revelation, and several other reasons, to believe with
assurance that there are such creatures: but our senses not being able to discover them, we want
the means of knowing their particular existences. For we can no more know that there are finite
spirits really existing, by the idea we have of such beings in our minds, than by the ideas any one
has of fairies or centaurs, he can come to know that things answering those ideas do really exist.
And therefore concerning the existence of finite spirits, as well as several other things, we must
content ourselves with the evidence of faith; but universal, certain propositions concerning this
matter are beyond our reach. For however true it may be, v.g., that all the intelligent spirits that God
ever created do still exist, yet it can never make a part of our certain knowledge. These and the like
propositions we may assent to, as highly probable, but are not, I fear, in this state capable of
knowing. We are not, then, to put others upon demonstrating, nor ourselves upon search of
universal certainty in all those matters; wherein we are not capable of any other knowledge, but
what our senses give us in this or that particular.
13. Only particular propositions concerning concrete existences are knowable. By which it appears
that there are two sorts of propositions:--(1) There is one sort of propositions concerning the
existence of anything answerable to such an idea: as having the idea of an elephant, phoenix,
motion, or an angel, in my mind, the first and natural inquiry is, Whether such a thing does
anywhere exist? And this knowledge is only of particulars. No existence of anything without us, but
only of God, can certainly be known further than our senses inform us. (2) There is another sort of
propositions, wherein is expressed the agreement or disagreement of our abstract ideas, and their
dependence on one another. Such propositions may be universal and certain. So, having the idea of
God and myself, of fear and obedience, I cannot but be sure that God is to be feared and obeyed by
me: and this proposition will be certain, concerning man in general, if I have made an abstract idea
of such a species, whereof I am one particular. But yet this proposition, how certain soever, that
"men ought to fear and obey God" proves not to me the existence of men in the world; but will be
true of all such creatures, whenever they do exist: which certainty of such general propositions
depends on the agreement or disagreement to be discovered in those abstract ideas.
14. And all general propositions that are known to be true concern abstract ideas. In the former
case, our knowledge is the consequence of the existence of things, producing ideas in our minds by
our senses: in the latter, knowledge is the consequence of the ideas (be they what they will) that are
in our minds, producing there general certain propositions. Many of these are called aeternae
veritates, and all of them indeed are so; not from being written, all or any of them, in the minds of al
men; or that they were any of them propositions in any one's mind, till he, having got the abstract
ideas, joined or separated them by affirmation or negation. But wheresoever we can suppose such a
creature as man is, endowed with such faculties, and thereby furnished with such ideas as we have,
we must conclude, he must needs, when he applies his thoughts to the consideration of his ideas,
know the truth of certain propositions that will arise from the agreement or disagreement which he
will perceive in his own ideas. Such propositions are therefore called eternal truths, not because
they are eternal propositions actually formed, and antecedent to the understanding that at any time
makes them; nor because they are imprinted on the mind from any patterns that are anywhere out
of the mind, and existed before: but because, being once made about abstract ideas, so as to be
true, they will, whenever they can be supposed to be made again at any time, past or to come, by a
mind having those ideas, always actually be true. For names being supposed to stand perpetually
for the same ideas, and the same ideas having immutably the same habitudes one to another,
propositions concerning any abstract ideas that are once true must needs be eternal verities.