Aristoxenus, through Plato's dialogue Phaedo, Aristotle, Saint Augustine in his thesis on music, and Aquinas; and in the Florentine Renaissance, Marsilio Ficino in his work on the immortality of the soul, the Theologia Platonica.

Thus there are many references which filter through into Shakespeare's plays and sonnets derived from this body of thought; particularly in the description of important characters, and to the power of music above all to 'charm the savage breast', adjust the elements, and restore the equilibrium and balance, the