For those who can't bring it to mind: When Cain killed his brother, God banished him and "marked him" as punishment, so that wherever he went, people would recognize him by the mark and know what he did. However, I am a little confused as to the original question. When have i thought about it, or when was I taught about it? Or is the question what I think about it and what it is? A little clarification would be wonderful, thank you. :)