One becomes immortal when one outgrows the fear of death. Markandeya does at the age of sixteen when he clings to the Shiva-linga, which is the symbol of Purusha or spiritual reality. This is a metaphor for faith. Faith is not rational just as immortality is not natural. Immortality is an idea that appears in the human imagination in response to the fear of death. When one liberates oneself from the fear of death using faith, one becomes indifferent to death. Death then no longer controls us or frightens us. We are liberated. We achieve immortality.
