The Republic by Plato Part 3 Page 48

Not at all, he replied.

And so, by the dog of Egypt, we have been unconsciously purging the State, which not long ago we termed luxurious.

And we have done wisely, he replied.

Then let us now finish the purgation, I said. Next in order to harmonies, rhythms will naturally follow, and they should be subject to the same rules, for we ought not to seek out complex systems of metre, or metres of every kind, but rather to discover what rhythms are the expressions of a courageous and harmonious life; and when we have found them, we shall adapt the foot and the melody to words having a like spirit, not the words to the foot and melody. To say what these rhythms are will be your duty — you must teach me them, as you have already taught me the harmonies.