I think of moral beauty as what is the good and the just - terms perhaps best defined by their opposite: evil. Evil is the willingness to do damage to the other; its maximal expression is murder, but it includes a great deal of subtle and not-so-subtle injuries as it advances to that extreme. Evil acts reduce the other to an object, a being to its component parts, and obliterate subjectivity. Evil's breeding ground is a lack of empathy.