and speculation, to
see if they possibly could admit of doubt. Then doubts crowded upon me
in such numbers that my incertitude became complete. Whence results the
confidence I have in sensible things? The strongest of all our senses is
sight; and yet, looking at a shadow, and perceiving it to be fixed and
immovable, we judge it to be deprived of movement; nevertheless,
experience teaches us that, when we return to the same place an hour
after, the shadow is displaced, for it does not vanish suddenly, but
gradually, little by little, so as never to be at rest. If we look at
the stars, they seem to be as small as money-pieces; but mathematical
proofs convince us that they are larger than the earth. These and other
things are judged by the senses, but rejected by reason as false. I
abandoned the senses, therefore, having seen all my confidence in their
truth shaken.

"'Perhaps,' said I, 'there is no assurance but in the notions of reason,
that is to say, first principles, as that ten is more than three; the
same thing cannot have been created and yet have existed from all
eternity; to exist and not to exist at the same time is impossible.'

[Sidenote: Fallibility of reason.] "Upon this the senses replied, 'What
assurance have you that your confidence in reason is not of the same
nature as your confidence in us? When you relied on us, reason stepped
in and gave us the lie; had not reason been there, you would have
continued to rely on us. Well, may there not exist some other judge
superior to reason, who, if he appeared, would refute the judgments of
reason in the same way that reason refuted us? The non-appearance of
such a judge is no proof of his non-existence.'

[Sidenote: The nature of dreams.] "I strove in vain to answer the
objection, and my difficulties increased when I came to reflect on
sleep. I said to myself, 'During sleep, you give to visions a reality
and consistence, and you have no suspicion of their untruth. On
awakening, you are made aware that they were nothing but visions. What
assurance have you that all you feel and know when you are awake does
actually exist? It is all true as respects your condition at that
moment; but it is nevertheless possible that another condition should
present itself which should be to your awakened state that which to your
awakened state is now to you sleep; so that, as respects this higher
condition, your waking is but sleep.'"

It would not be possible to find in any Eu