Q 2: What is Nadi Suddhi in its technical sense? How to feel that one has attained perfect Nadi Suddhi?
A: Nadi Suddhi means purification of the nerves (Nadis). Nerve is not the correct English term for Nadi. There is no appropriate word for Nadi in English. Complete fast, preferably without any liquid or solid food, practice of Asanas and Pranayama, and intense physical exercise– all go a long way in the elimination of fat and other unwanted matters and in the overhauling of the system to confer the benefit of Nadi Suddhi. Asanas and Pranayama can purify the
nerves, if done with the correct technique. When one attains Nadi Suddhi, the body becomes light. Stool becomes scanty. There is agility in movement and activity in demeanor. No trace of slothfulness or indolence can be detected. While walking, the body appears to be floating in the air. The tone of the voice
changes from hoarseness or gruffness to mellifluence. Hopping, jumping and dancing while at work can be observed in one endowed with Nadi Suddhi. Something inexpressible forces the person to do this and to achieve something grand in his lifetime.
– Sri Swami Sivananda