adapted to nature. For otherwise, the desire, (for that is how I translate ὁρμὴ,) 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 ἀπόδειξις, 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 discovered anything? Or what trust could be placed in an argument when brought to a conclusion? And what end will philosophy itself have, which is bound to proceed according to reason? And what will become of wisdom? which ought not to doubt about its own character, nor about its decrees, which philosophers call δόγματα; none of which can be betrayed without wickedness. For when a decree is betrayed, the law of truth
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