The abyss is the greatest challenge of the journey. They must overcome their greatest fears, and give themselves up to the journey. If they don't do this, they may not conquer the abyss.
The abyss in Shrek is when he leaves Fiona for Lord Farquaad to get married. He does this because he overhears Fiona saying how ugly she is when she becomes an ogre, and he thinks she is saying it about him. He leaves Fiona and Donkey and goes back to his swamp heartbroken.
The abyss in Shrek is when he leaves Fiona for Lord Farquaad to get married. He does this because he overhears Fiona saying how ugly she is when she becomes an ogre, and he thinks she is saying it about him. He leaves Fiona and Donkey and goes back to his swamp heartbroken.