A man should have aim, but must not have ambition. Aim is plural. Ambition is singular. There is a single post of president or prime minister. It is a single chair. But aspirants are many. As such it is the story of depriving, wounding or murdering of contesting candidates even. Politics, throne, imperialism all are the outcome of ambition. Newton, Shakespeare are the outcome of aim. Adolf Hitler is the outcome of ambition.