10 Finally, do not even the leaders and founders of the schools already mentioned, say those very things which they do say through belief in their own ideas? For, did Heraclitus see things produced by the changes of fires? Thales, by the condensing of water? Did Pythagoras see them spring from number? Did Plato see the bodiless forms? Democritus, the meeting together of the atoms? Or do those who assert that nothing at all can be comprehended by man, know whether what they say is true, so as to understand that the very proposition which they lay down is a declaration of truth? Since, then, you have discovered and learned nothing, and are led by credulity to assert all those things which you write, and comprise in thousands of books; what kind of judgment, pray, is this, so unjust that you mock faith in us, while you see that you have it in common with our readiness of belief? But you say you believe wise men, well versed in all kinds of learning!— those, forsooth, who know nothing, and agree in nothing which they say; who join battle with their opponents on behalf of their own opinions, and are always contending fiercely with obstinate hostility; who, overthrowing, refuting, and bringing to nought the one the other's doctrines, have made all things doubtful, and have shown from their very want of agreement that nothing can he known.
Source: Against the Heathen (New Advent)