And the considerations which we have urged seem to show in what way these fifty years' old choristers who are to sing, may be expected to be better trained.

For they need to have a quick perception and knowledge of harmonies and rhythms; otherwise, how can they ever know whether a melody would be rightly sung to the Dorian mode, or to the rhythm which the poet has assigned to it?
CLEINIAS: Clearly they cannot.
ATHENIAN: The many are ridiculous in imagining that they know what is in proper harmony and rhythm, and what is not, when they can only be made to sing and step in rhythm by force; it never occurs to them that they are ignorant of what they are doing.

Now every melody is right when it has suitable harmony and rhythm, and wrong when unsuitable.
CLEINIAS: That is most certain.
ATHENIAN: But can a man who does not know a thing, as we were saying, know that the thing is right?
CLEINIAS: Impossible.
ATHENIAN: Then now, as would appear, we are making the discovery that our newly-appointed choristers, whom we hereby invite and, although they are their own masters, compel to sing, must be educated to such an extent as to be able to follow the steps of the rhythm and the notes of the song, that they may know the harmonies and rhythms, and be able to select what are suitable for men of their age and character to sing; and may sing them, and have innocent pleasure from their own performance, and also lead younger men to welcome with dutiful delight good dispositions.

Having such training, they will attain a more accurate knowledge than falls to the lot of the common people, or even of the poets themselves.

For the poet need not know the third point, viz., whether the imitation is good or not, though he can hardly help knowing the laws of melody and rhythm.