Source: June is, among other things, Black Music Month, and if we’re going to talk about Black music, we have to talk about protest music. But if we’re going to talk about protest music, we have to talk about sacrifice, and if we’re going to talk about Black music, protest music and what was sacrificed to make it great, we have to talk about Nina Simone and Sam Cooke, two artists who decided the message was more important than their commercial s…