A Jedi's first true battle is with oneself, and no one else. Only when you have done this can you truly become a Jedi.

You cannot control it, you will be tempted! Don't give into hate it leads to the dark side!

One of the major themes running throughout Master Skywalker's tale is Luke's battle with himself. Luke finally won the battle when faced with killing his own father, he said no and turned away from the dark side of the force. At this point the emperor knew that he was lost to the Dark side and decided to have him killed. Luke had to overcome the hatred, fear and anger (emotions of the darkside) he felt toward his father and forgive him for all that he had done (destroyed the Jedi, tortured his friends, killing Ben, though probably most importantly abandoning Luke as a child and failing to be a father to him).

Fighting the battle with the darkness within was the lesson of the tree where the dark side was strong. When Luke entered he asked "What is in there?" and Yoda replied "Only what you take with you." In other words the tree merely reflected and brought out the place were the dark side resided within Luke, that is his feeling towards his father. Striking Darth Vader down in the tree, signified Luke killing himself or more importantly failing the test of a Jedi to turn away from the Dark side. As already mentioned, when Luke latter forgave his father and refused to kill his father he successfully turned away from the Dark side.

If you wish to become a Jedi, you must face those places of pain, anger and mistrust within you, places where the dark side of the force grows and lingers. You must forgive those that have harmed you in the past and truly Love them. For unless you do this, no matter how much physical and mental training you will do you will be at risk of falling to the ways of the Darkside.

You must first battle the foe within before you can help others.

May the Force be with you...