sight believes the earth to be motionless and sees the sun in motion, and
in many similar cases it makes mistakes. Therefore, we cannot trust it.

The second is the method of reason, which was that of the ancient
philosophers, the pillars of wisdom; this is the method of the
understanding. They proved things by reason and held firmly to logical
proofs; all their arguments are arguments of reason. Notwithstanding this,
they differed greatly, and their opinions were contradictory. They even
changed their views--that is to say, during twenty years they would prove
the existence of a thing by logical arguments, and afterward they would
deny it by logical arguments--so much so that Plato at first logically
proved the immobility of the earth and the movement of the sun; later by
logical arguments he proved that the sun was the stationary center, and
that the earth was moving. Afterward the Ptolemaic theory was spread
abroad, and the idea of Plato was entirely forgotten, until at last a new
observer again called it to life. Thus all the mathematicians disagreed,
although they relied upon arguments of reason. In the same way, by logical
arguments, they would prove a problem at a certain time, then afterward by
arguments of the same nature they would deny it. So one of the
philosophers would firmly uphold a theory for a time with strong arguments
and proofs to support it, which afterward he would retract and contradict
by arguments of reason. Therefore, it is evident that the method of reason
is not perfect, for the differences of the ancient philosophers, the want
of stability and the variations of their opinions, prove this. For if it
were perfect, all ought to be united in their ideas and agreed in their
opinions.

The third method of understanding is by tradition--that is, through the
text of the Holy Scriptures--for people say, "In the Old and New
Testaments, God spoke thus." This method equally is not perfect, because
the traditions are understood by the reason. As the reason itself is
liable to err, how can it be said that in interpreting the meaning of the
traditions it will not err, for it is possible for it to make mistakes,
and certainty cannot be attained. This is the method of the religious
leaders; whatever they understand and comprehend from the text of the
books is that which their reason understands from the text, and not
necessarily the real truth; for the reason is like a balance, and the
meanings contained in