Plato in his 'Republic’ sets down the study of music and its regulation as an essential part of the ideal commonwealth. 'Beginning from early childhood,’ he says, 'they teach and admonish their sons as long as they live....’ 'Again the music masters in the same way pay attention to sobriety of behavior and take care that the boys commit no evil, and when they have learned to play upon the lyre they teach them all the compositions of other good poets, lyric poets, setting them to music, and they compel Modes and Harmony to become familiar to the boys’ souls in order that they may become more gentle, and, being themselves more rhythmical and harmonious, they may be serviceable in word and deed; for the whole life of man requires rhythm and harmony.’ And elsewhere in the same work: 'But when handsome amusements are appointed them in their infancy, and when by means of music they embrace that amusement which is according to law (contrariwise to the others), this music attends them in everything else and grows with them, and raiseth up in the city whatever formerly was fallen down.’ As illustrative of the moral import of music Plato says: 'Is it indeed then according as I say, that we shall never become musicians, neither we ourselves, nor the guardians we say we are to educate, before we understand the images of temperance, fortitude, liberality and magnificence, and the other sister virtues?...’ Hierocles attests Pythagoras’ belief in the therapeutic powers of music in the following quotation: 'He look’d on Musick as a great advantage to Health and made use of it in the diseases of the body as well as of the Soul; for, as Plato said after him, Perfect Musick is a Compound of Voices and of Instrumental Harmony. The Voice alone is more perfect than instruments alone; but it wants one thing to complete its Perfection; and that one thing is Harmony: and Instruments alone, without a voice, yield only rambling and extravagant Sounds, which may indeed affect and move the Soul, but cannot instruct nor form the Manners which ought to be the chief end of Musick.’[33]