time travelling

If i could travel back to any time in history I could change the world... I could make it a better place, a safer place, a less hurtful place. I could make a world where every man could live in harmony and peace with his fellow humans, I could stop violence, war, and cruelty. So I decided to go back to the beginning of this period. Imagine all the good i could('nt) do if i went back! I could give myself a better idea of what to write on this essay, I could do...other things. I could go outside and buy groceries or get a new shirt.... Then I could takeover the universe.