At age 16, he heard somebody mention "Arunachala." Although he didn't know what the word meant (it's the name of a holy hill associated with the god Shiva) he became greatly excited. At about the same time he came across a copy of Sekkilar's Periyapuranam, a book that describes the lives of Shaivite saints, and became fascinated by it. In the middle of 1896, at age 16, he was suddenly overcome by the feeling that he was about to die. He lay down on the floor, made his body stiff, and held his breath. "My body is dead now," he said to himself, "but I am still alive." In a flood of spiritual awareness he realized he was spirit, not his body.
Ramana Maharshi taught a method called self-inquiry in which the seeker focuses continuous attention on the I-thought in order to find its source. In the beginning this requires effort, but eventually something deeper than the ego takes over and the mind dissolves in the heart center.