compelled by necessity to suppose that they exist, and seek
their own advantage, and often affirm and deny, even with an
oath.  (2) If they deny, grant, or gainsay, they know not that
they deny, grant, or gainsay, so that they ought to be
regarded as automata, utterly devoid of intelligence.

[49] (1) Let us now return to our proposition.  (2) Up to the present,
we have, first, defined the end to which we desire to direct all our
thoughts; secondly, we have determined the mode of perception best
adapted to aid us in attaining our perfection; thirdly, we have
discovered the way which our mind should take, in order to make a good
beginning - namely, that it should use every true idea as a standard in
pursuing its inquiries according to fixed rules.  (49:3) Now, in order
that it may thus proceed, our method must furnish us, first, with a
means of distinguishing a true idea from all other perceptions, and
enabling the mind to avoid the latter; secondly, with rules for
perceiving unknown things according to the standard of the true idea;
thirdly, with an order which enables us to avoid useless labor.
(49:4) When we became acquainted with this method, we saw that,
fourthly, it would be perfect when we had attained to the idea of the
absolutely perfect Being.  (5) This is an observation which should be
made at the outset, in order that we may arrive at the knowledge of
such a being more quickly. 

[50] (1) Let us then make a beginning with the first part of the method,
which is, as we have said, to distinguish and separate the true idea
from other perceptions, and to keep the mind from confusing with true
ideas those which are false, fictitious, and doubtful.  (2) I intend to
dwell on this point at length, partly to keep a distinction so necessary 
before the reader's mind, and also because there are some who doubt of
true ideas, through not having attended to the distinction between a true
perception and all others.  (3) Such persons are like men who, while they
are awake, doubt not that they are awake, but afterwards in a dream, as
often happens, thinking that they are surely awake, and then finding that
they were in error, become doubtful even of being awake.  (4) This state
of mind arises through neglect of the distinction between sleeping and
waking.

[51]  (1) Meanwhile, I give warning that I shall not here give 
essence of every perception, and explain it through its proximate
cause.  (2) Such work lies in the province of philosophy.  (3) I shall
confine myself to what concerns method - that is, to the character of
fictitious, false and doubtful perceptions, and the means of freeing
ourselves therefrom.  (4) Let us then first inquire into the nature of
a fictitious idea. 

[52]  (1) Every perception has for its object either a thing considered
as existing, or solely the essence of a thing.  (2) Now "fiction" is
chiefly occupied with things considered as existing.  (3) I will,
therefore, consider these first - I mean cases where only the existence
of an object is feigned, and the thing thus feigned is understood, or
assumed to be understood.  (4) For instance, I feign that Peter, whom
I know to have gone home, is gone to see me, [r] or something of that
kind.  (5) With what is such an idea concerned?  (6) It is concerned
with things possible, and not with things necessary or impossible. 

[53] (1) I call a thing impossible when its existence would imply a
contradiction; necessary, when its non-existence would imply a
contradiction; possible, when neither its existence nor its
non-existence imply a contradiction, but when the necessity or
impossibility of its nature depends on causes unknown to us, while
we feign that it exists.  (2) If the necessity or impossibility of
its existence depending on external causes were known to us, we
could not form any fictitious hypotheses about it; 

[54] (1) Whence it follows that if there be a God, or omniscient
Being, such an one cannot form fictitious hypotheses.  (2) For,
as regards ourselves, when I know that I exist, [s] I cannot
hypothesize that I exist or do not exist, any more than I can
hypothesize an elephant that can go through the eye of a needle;
nor when I know the nature of God, can I hypothesize that He 
or does not exist. [t]  (54:3) The same thing must be said of the
Chimaera, whereof the nature implies a contradiction.  (4) From
these considerations, it is plain, as I have already stated, that
fiction cannot be concerned with eternal truths. [u]

[55]  (1) But before proceeding further, I must remark, in passing,
that the difference between the essence of one thing and the essence
of another thing is the same as that which exists between the reality
or existence of one thing and the reality or existence of another;
therefore, if we wished to conceive the existence, for example,
of Adam, simply by means of existence in general, it would be the
same as if, in order to conceive his existence, we went back to the
nature of being, so as to define Adam as a being.  (2) Thus, the more
existence is conceived generally, the more is it conceived confusedly
and the more easily can it be ascribed to a given object.
(55:3) Contrariwise, the more it is conceived particularly, the more
is it understood clearly, and the less liable is it to be ascribed,
through negligence of Nature's order, to anything save its proper
object.  (4) This is worthy of remark. 

[56]  (1) We now proceed to consider those cases which are commonly
called fictions, though we clearly understood that the thing is not
as we imagine it.  (2) For instance, I know that the earth is round,
but nothing prevents my telling people that it is a hemisphere,
and that it is like a half apple carved in relief on a dish; or,
that the sun moves round the earth, and so on.  (56:3) However,
examination will show us that there is nothing here inconsistent
with what has been said, provided we first admit that we may have
made mistakes, and be now conscious of them; and, further, that we