Guru is the door to spiritual liberation, but it is the aspirant who has to enter it through niskama karma- righteous words, thoughts and actions performed without the expectation of results. Also a total surrender, a strong faith and a firm devotion towards the Guru is needed. He must perform service to others without the expectation of positive results or any kind of reward. To light a candle, you need a burning candle. An illumined soul alone can enlighten another soul.