The sense of 'I' pertains to the person, the body and brain. When a man knows his true Self for the first time something else arises from the depths of his being and takes possession of him. That something is behind the mind; it is infinite, divine, eternal. Some people call it the Kingdom of Heaven, others call it the soul and others again Nirvana, and Hindus call it Liberation; you may give it what name you wish. When this happens a man has not really lost himself; rather he has found himself.