One of the meaning of the word Guru is ‘heavy’–heavy by taking the burden of karma from the disciple. All human being carry the burden of karmas right from being a single celled creature. It is the force of karma that makes a person act as well as experience pain and misery. And spirituality is all about wiping out karmas.
Many a times the density of karmas prevent us from experiencing our true selves. It is like thick dust on a mirror preventing it from reflecting sunlight. It is exactly here that the need of true guru is felt. A true guru by being compassionate takes upon himself many of your karma so that you are able to sit still for meditation. Also when students go into deep meditation by leaving the conscious mind he might encounter many unexpected memories and experiences. Here a Shiva like guru takes the poison of karmas upon himself otherwise you will crack. This is exactly what is meant by SAMUDRA MANTHAN or CHURNING THE OCEAN OF MILK.
When consciousness is churned many things both good and evil comes up and the student may not be prepared to deal with such things. And the true guru makes a drink of it. The word Enlightenment in tis context has a clear meaning–REDUCING THE WEIGHT OF YOUR KARMAS.
It is generally said that when the student is ready a teacher appears or sometimes teachers also seek out students. Anyways it is always best to have a guru to lead us in this dark world where LIFE IS A BRIEF HAPPENING.