Is the ideal of a United Nations "an impossible" dream"?
(Look for the Present Perfect Tense being used here)

People have always dreamed of living in a peaceful world with enough resources for all people to share. But can this ever become a reality? People have always been able to dream things long before being able to do them. A dream can take place at lightning speed, while reality is limited by time and space.

The League of Nations may have failed, but that was not the end of the dream of a united world. The creation of the United Nations followed. The mere fact that a "United Nations" came into existence represents a giant step in the human social evolution. Throughout history, it has often seemed that human progress--on both an individual and a collective level - takes two steps forward and one step back. But it keeps going forward. The important thing is not to give up when success is long in coming -- but to stay focused on the goal. Every positive human invention that has been created in the world started as an individual or collective dream. Those who have persisted in making their dreams a reality over time have often been rewarded by seeing their dreams spring to life in the world. Persistence is key. As U.S President Calvin Coolidge once said, "Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan, 'press on' has solved, and always will solve, the problems of the human race." .