assent, being nevertheless agitated and excited to action, he leaves
us perceptions of the sort by which we are excited to action, and those
owing to which we can, when questioned, answer either way, being guided
only by appearances, as long as we avoid expressing a deliberate assent.
And yet we must look upon all appearances of that kind as probable, but
only those which have no obstacles to counteract them. If we do not induce
you to approve of these ideas, they may perhaps be false, but they
certainly do not deserve odium. For we are not depriving you of any light;
but with reference to the things which you assert are perceived and
comprehended, we say, that if they be only probable, they appear to be
true.

XXXIII. Since, therefore, what is probable, is thus inferred and laid
down, and at the same time disencumbered of all difficulties, set free and
unrestrained, and disentangled from all extraneous circumstances; you see,
Lucullus, that that defence of perspicuity which you took in hand is
utterly overthrown. For this wise man of whom I am speaking will survey
the heaven and earth and sea with the same eyes as your wise man; and will
feel with the same senses all those other things which fall under each
respective sense. That sea, which now, as the west wind is rising over it,
appears purple to us, will appear so too to our wise man, but nevertheless
he will not sanction the appearance by his assent; because, to us
ourselves it appeared just now blue, and in the morning it appeared
yellow; and now, too, because it sparkles in the sun, it is white and
dimpled, and quite unlike the adjacent continent; so that, even if you
could give an account why it is so, still you could not establish the
truth of the appearance that is presented to the eyes.

Whence then,--for this was the question which you asked,--comes memory, if
we perceive nothing, since we cannot recollect anything which we have seen
unless we have comprehended it? What? Did Polyaenus, who is said to have
been a great mathematician, after he had been persuaded by Epicurus to
believe all geometry to be false, forget all the knowledge which he had
previously possessed? But that which is false cannot be comprehended as
you yourselves assert. If, therefore, memory is conversant only with
things which have been perceived and comprehended, then it retains as
comprehended and perceived all that every one remembers. But nothing false
can be comprehended; and Scyron