down in the first place a principle which wisdom may follow when it begins
to act; and that principle must be adapted to nature. For otherwise, the
desire, (for that is how I translate {~GREEK SMALL LETTER OMICRON WITH DASIA~}{~GREEK SMALL LETTER RHO~}{~GREEK SMALL LETTER MU~}{~GREEK SMALL LETTER ETA WITH VARIA~},) by which we are impelled to
act, and by which we desire what has been seen, cannot be set in motion.
But that which sets anything in motion must first be seen and trusted,
which cannot be the case if that which is seen cannot be distinguished
from what is false. But how can the mind be moved to desire anything, if
it cannot be perceived whether that which is seen is adapted to nature or
inconsistent with it?

And again, if it does not occur to a man's mind what his duty is, he will
actually never do anything, he will never be excited to any action, he
will never be moved. But if he ever is about to do anything, then it is
necessary that that which occurs to him must appear to him to be true.
What! But if those things are true, is the whole of reason, which is, as
it were, the light and illumination of life, put an end to? And still will
you persist in that wrong-headedness? For it is reason which has brought
men the beginning of inquiry, which has perfected virtue, after reason
herself had been confirmed by inquiry. But inquiry is the desire of
knowledge; and the end of inquiry is discovery. But no one can discover
what is false; nor can those things which continue uncertain be
discovered. But when those things which have, as it were, been under a
veil, are laid open, then they are said to be discovered; and so reason
contains the beginning of inquiry, and the end of perceiving and
comprehending. Therefore the conclusion of an argument, which in Greek is
called {~GREEK SMALL LETTER ALPHA WITH PSILI~}{~GREEK SMALL LETTER PI~}{~GREEK SMALL LETTER OMICRON WITH OXIA~}{~GREEK SMALL LETTER DELTA~}{~GREEK SMALL LETTER EPSILON~}{~GREEK SMALL LETTER IOTA~}{~GREEK SMALL LETTER XI~}{~GREEK SMALL LETTER IOTA~}{~GREEK SMALL LETTER FINAL SIGMA~}, is thus defined:--Reason, which leads one from facts
which are perceived, to that which was not perceived.

IX. But if all things which are seen were of that sort that those men say
they are, so that they either could possibly be false, or that no
discernment could distinguish whether they were false or not, then how
could we say that any one had either formed any conclusion, or discov