 Both Plato and Aristotle comment on the value of instrumental music. Plato’s pragmatic attitude grounds his injunction against complexity and subtlety in music (Republic, 3.399c-e). He holds that music should have a vocal part, and argues that the musical elements should conform to the emotional state described by the piece’s lyrical content (Republic, 3.400d). This concern with clear and unequivocal musical imitation also motivates Plato’s stance on the value of instrumental music. While it is clear that Plato holds the purely musical elements of melody and rhythm to have an imitative potential, he attributes little value to instrumental music, presumably because he believes that it is unable to provide an unequivocal imitation of courage and moderation (Laws 2.669 d-e).