One reason that I can think of is that you already had a mongod running on port 27017 without the --replSet argument before you tried starting it with. Make sure no mongod is running ( ps aux |grep mongod ) before you try this. I would also inspect the log file as it is likely that it gives a clue why it did not start in replica-set mode.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.