Sextus Empiricus Pyrrhoniae Hypotyposes 2.5.40

[40] For inasmuch as sagacity is liable to a great, indeed almost incalculable, advance or decline in intensity, we assert that it is possible for another man to arise who is more sagacious than this man who, we say, is more sagacious than those of the past and present. So, then, just as we are requested to believe the man who is now said to be wiser than those of the present and the past because of his sagacity, so it is still more proper to believe his successor in the future who will be more sagacious than he. And when that successor has arisen, then it is right to expect that yet another will arise more sagacious than he, and so on ad infinitum.