The phrase is "Music has charms to soothe a savage breast" and not "beast" as many people think. The phrase comes from the play "The Mourning Bride" by William Congreve, a poet of the restoration period and an English playwright. The actual quote reads "Musick has Charms to sooth a savage Breast, To soften Rocks, or bend a knotted Oak". The phrase means that music has the power to enchant even the roughest of people. It is often used to describe the calming effect of music on people who are angry or upset.