Imagine there's no Heaven, It's easy if you try.No hell below us.Above us only sky.Imagine all the people living for today.Imagine there's no countries.It isn't hard to do.Nothing to kill or die...
It was about if there wasn't anything separating each one of us (religion, etc.) the world would be a better place. To put it plainly, Imagine is a plea for world peace and Lennon was simply stating...