CLEINIAS: Undoubtedly.
ATHENIAN: But if some things are commensurable and others wholly incommensurable, and you think that all things are commensurable, what is your position in regard to them?
CLEINIAS: Clearly, far from good.
ATHENIAN: Concerning length and breadth when compared with depth, or breadth and length when compared with one another, are not all the Hellenes agreed that these are commensurable with one another in some way?
CLEINIAS: Quite true.
ATHENIAN: But if they are absolutely incommensurable, and yet all of us regard them as commensurable, have we not reason to be ashamed of our compatriots; and might we not say to them: O ye best of Hellenes, is not this one of the things of which we were saying that not to know them is disgraceful, and of which to have a bare knowledge only is no great distinction?
CLEINIAS: Certainly.
ATHENIAN: And there are other things akin to these, in which there spring up other errors of the same family.
CLEINIAS: What are they?
ATHENIAN: The natures of commensurable and incommensurable quantities in their relation to one another. A man who is good for anything ought to be able, when he thinks, to distinguish them; and different persons should compete with one another in asking questions, which will be a far better and more graceful way of passing their time than the old man's game of draughts.