Just like a fire damages a forest [MET], when we say things that are evil, we harm many people. What we say [MTY] reveals that we are very evil. What we say contaminates/defiles everything that we think and do [PRS, MET]. Just like a flame of fire easily causes the whole surrounding area [MET] to burn, what we say [MTY] can cause others to want to do evil. It is the devil himself [MTY] who causes us to say evil things.