The past.
How many of you want to go back to the past? To see your loved ones that left you alone. To re-experience those excitement and happiness of childhood, which are nonexistent in the adult world. To escape the harsh present.
But how many of you realized that the past is and will be the past. No matter how hard you want to go back to the past, you can't flip the time table.
Don't make yourself immersed in the past anymore. It's time to move on. But don't forget the past, for it is the foundation for building the future.