The "I" is the root thought behind all thoughts. In meditation it is possible to isolate it and it remains the only witness of perception. By taking a step further and suppressing it, the cessation of the mind and the exit from Duality is produced, this is when one enters the plane of Nirvana. The technique is simple, it requires perfect concentration and relaxation. Difficult, but not impossible. The very cause of the mind, the root thought "I", is at the same time the exit from the state of conditioned existence to the Absolute. There is no practice or theory superior to this. You must experience, if you fail to isolate your root thought I, your concentration is still deficient and your nervous system is impure. You must discharge your accumulated stress. You can do this through the Vipassana or Synaptic technique, also through the Kriyas. When your mind is pure you will enjoy perfect concentration and achieve the goal. You must train to achieve the goal.