And when these principles are laid down, then these men comprehend the whole cause in the conclusion of one argument. But this conclusion, thus compounded, runs in this way: “Of the things which are seen, some are true and some are false; and what is false cannot be perceived, but that which appears to be true is all of such a character that a thing of the same sort may seem to be also false. And as to those things which are perceived being of such a sort that there is no difference between them, it cannot possibly happen that some of them can be perceived, and that others cannot; there is, then, nothing seen which can really be perceived.”
But of the axioms which they assume, in order to draw the conclusions which they desire, they think that two ought to be granted to them; for no one objects to them. They are these: “That those perceptions which are false, cannot really be perceived;” and the second is—“Of those perceptions between which there is no difference, it is impossible that some should be of such a character that they can be perceived, and others of such a character that they cannot.”
But their other propositions they defend by numerous and varied arguments, and they likewise are two in number. One is—“Of those things which appear, some are true and others false;” the other is—“Every perception which originates in the truth, is of such a character as it might be of, though originating in what is false.” And these two propositions they do not pass by, but they expand in such a manner as to show no slight degree of care and diligence. For they divide them into parts, and those also large parts; first of all into the senses, then into those things which are derived from the senses, and from universal custom, the authority of which they wish to invalidate. Then they come to the point of laying it down that nothing can be perceived even by reason and conjecture. And these universal propositions they cut up into more minute parts. For as in our yesterday's discussion you saw that they acted with respect to the senses, so do they also act with respect to everything else. And in each separate thing which they divide into the most minute parts, they wish to make out that all these true perceptions have often false ones added to them, which are in no respect different from the true ones; and that, as they are of such a character, nothing can be comprehended.
