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.
He who without the Muse's madness in his soul comes knocking at the door of poesy and thinks that art will make him anything fit to be called a poet, finds that the poetry which he indites in his sober senses is beaten hollow by the poetry of madmen.
In the world of knowledge, the essential Form of Good is the limit of our inquiries, and can barely be perceived; but, when perceived, we cannot help concluding that it is in every case the source of all that is bright and beautiful -in the visible world giving birth to light and its master, and in the intellectual world dispensing, immediately and with full authority, truth and reason -and that whosoever would act wisely, either in private or in public, must set this Form of Good before his eyes.
Do you, like a skilful weigher, put into the balance the pleasures and the pains, near and distant, and weigh them, and then say which outweighs the other? If you weigh pleasures against pleasures, you of course take the more and greater; or if you weigh pains against pains, then you choose that course of action in which the painful is exceeded by the pleasant, whether the distant by the near or the near by the distant; and you avoid that course of action in which the pleasant is exceeded by the painful.
Harmony sinks deep into the recesses of the soul and takes its strongest hold there, bringing grace also to the body & mind as well. Music is a moral law. It gives a soul to the universe, wings to the mind, flight to the imagination, a charm to sadness, and life to everything. It is the essence of order.
Each living creature is said to be alive and to be the same individual - as for example someone is said to be the same person from when he is a child until he comes to be an old man. And yet, if he's called the same, that's despite the fact that he's never made up from the same things, but is always being renewed, and losing what he had before, whether it's hair, or flesh, or bones, or blood, in fact the whole body.