Once there was a little soul who got very excited one day and ran to God and said, "I know who I am" And God said, "That's nice. Who are you?" The little soul said, "I am the light." And God said, "That's right. You are the light." The soul thought for a second and said, "But I want to be the light." God said, "But you are the light!" And the soul said, "I know I am the light but I want to be the light. I want to experience myself being the light. I want to know myself in my own experience."
God said, "Oh I see! You want to experience being who you already are." The little soul, "Yes, that's it. I want to experience myself being the light. Not just know it, but experience being the light." God replied, "That is understandable but it is a bit of a challenge, because you see there is nothing else BUT the light, for I have created naught but the light. You are as a candle in the sun. You are there with a billion billion billion other candles that make up the sun.... but the sun would not be the sun without you. Nay, it would be the sun without one of its candles and that would not be the sun at all. Yet how to know yourself as the light amidst the light is truly a puzzle," said God "Well," said the little soul, "you're God. Think of something!" And God said, "I will and I have. Here is what we will do. You cannot experience yourself as the light amidst the light, so we will surround you with that with which you are not. We will imagine together that which is not you and we will surround you with it, and we will call it the darkness. We will surround you with the darkness. We will surround you with the opposite of that which you are so that you may know in your experience how brightly you shine."
The little soul said, "Ok I am ready. Bring on the darkness. I can be the light!" God said, "I will, for you have asked for this and requested it. I will surround you with the darkness and yet in the moment that you find yourself so surrounded by the darkness, raise not your fist at heaven and curse the darkness not. Yet be a light unto the darkness that you may know who you really are, and that all whose lives you touch might know who they really are as well. Let your light so shine before men that they will see the glory of themselves reflected in you. You may do this with any aspect of divinity you wish," said God to the little soul. "So choose well and choose wisely in this and in your many lifetimes, for life has as its "soul" purpose the choosing and the Being of an aspect of Me that You Are."  God then said, "What do you then choose in this your next lifetime?" The little soul excitedly said, "Wow wow I can be anything you are!!" God said, "yes all of it or any part of it. Here are your choices. So, what do you choose?"
The little soul said, "You mean in the next lifetime I can be happy or joy or wisdom or peace or  love or or..."  "That is right," said God. Said the little soul, "I choose, I choose that! That is what I want to be. I want to experience that!"
God said, "My, my, my. This is your big day, for you have chosen forgiveness! You want to be forgiving?"
"Yes yes," said the little soul, "That is what I want to do. I want to experience myself as forgiveness."
"Well," said God, "there is only one problem. You see, there is no one to forgive."  "No one?" said the little soul. God replied, "Look around, do you see anyone less perfect less beautiful, less wondrous than you?"
And in that moment the little soul turned and saw that all the souls from the universe had gathered, for they had heard about the little souls discussion with God. And the soul looked around and all she saw was wonder and beauty and perfection even as she herself was perfection. She could see perfection all around, and the little soul said, "So I can see nothing but perfection all around. Who then shall I forgive, for there is none less perfect than I? How shall I experience forgiveness?"
Just then a friendly soul stepped forward from the crowd and said, "Do not despair. You can forgive me." The little soul said, "You? Who are you?"  The friendly soul replied, "I am one among many. I have chosen to step forward. I will provide you with someone to forgive in your next lifetime. I will do something in this, your next lifetime that you can forgive."
"What..what," said the little soul, "what will you do?" The friendly soul replied, "we will think of something."
"But, but why," said the little soul "would you do that, for you are an object of beauty as am I. A being of total perfection, whose light is produced by the very vibration of your blessed and glorious self. So rapidly do you vibrate and shine that I cannot gaze upon you. What would cause you to slow down your vibration to such a speed that you would become heavy enough to do this horrible thing? Why would you do that?"
And said the friendly soul, "It is quite simple. I would do it because I love you. And do not look so amazed you have done it for me as well. Do you not remember? Have you forgotten me so soon? We have danced this dance before you and I. We have danced this dance before. We have been the all of it do you not remember? We have been the up and the down of it, the left and the right of it, the before and the after. We have been the good and the bad of it. We all have been the all of it for each other. Surely you remember when I was the victim and you, you were the villain? Surely you remember? But you are right about one thing, it will not be easy slowing down my vibration exactly as you have described. It is not a simple matter. So I have only one favor to ask of you in this next lifetime that you may be forgiving." "What, what?" said the little soul, "I will do anything. anything! I get to experience myself as who I am. What could I possibly do for you in return?"  The friendly soul replied, "In the moment that I strike you and spite you. In the moment that I do the worst thing possible to you that you can imagine.... in that self same moment, remember who I really am. Because if you forget me as I am now, I will not remember myself at all. Worse yet you are liable to forget yourself too and then we will both have forgotten who we really are, Then we will need a third person to help us remember."  The little soul replied, "I will not forget. I will not forget. I will remember even in the worst moment."   
Credit for the little soul story goes to Neale Donald Walsh