Because, unlike courage and wisdom, which made our state brave and wise by being present in a particular part of it, discipline operates by being diffused throughout the whole of it. It produces a concord between its strongest and weakest and middle elements, whether you define them by the standard of good sense, or of strength, or of numbers or money or the like. And so we are quite justified in regarding discipline as this sort of natural harmony and agreement between higher and lower about which of them is to rule in state and individual.