Tattwa Bodha ends with the thought that with the knowledge of who I am or who the self is, we become free from the bondage of all actions. Actions are of three types—those that are done in the past that come to torment us as thoughts in the present, those that are being done right now, and those that we plan to do or compulsorily do in future.
Moving from this thought, the Atma Bodha of Sri Adisankaracharya shows us the secret super highway to liberation. Freedom from the binding compulsion to act is liberation. Of all the many practices to achieve such relaxation from the need to work, bodha or knowledge is the super highway. It is the only direct path. Other methods to liberation are circuitous.
The other ways are Karma Yoga which means offering our actions to the divine without any particular expectation of specific results to make us happy. Bhakti Yoga is uniting with the divine through prayer, turning the rosary, visiting temples and other places of pilgrimage, offering charities, doing yagnas and other rituals, observing fasts and doing penance. These actions grant a liberated state of mind by making it quiet. However, the quietness lasts only until the effect of the action. Once time passes by, the normal thoughts that plague the mind return to continue their disturbing dance.
In the case of knowledge of the self however, liberation happens instantly. How quick and how important is it? Sri Adisankaracharya gives a beautiful simile. Knowledge is like the fire that cooks food. Just as food cannot be cooked without fire, a refined state of mind that alone gives the taste of peace is not achieved without the fire of knowledge.
When the word knowing is used here, it is not any kind of knowledge like physics, chemistry, astronomy, astrology. The knowledge is about the core content of what makes you and me. That core is the same for all human beings, animals, plants, trees, insects and birds. It is the same for earth, water, fire, air and space. If that is known, then everything that needs to be known is known.
Ignorance or not knowing something can never keep the mind peaceful. Try sitting with someone who knows some special secret and is not sharing it with you. Your mind will be agitated. With the knowledge of the world however, knowing everything is not possible. There is always something that remains unknown. So the mind can never be everlastingly peaceful with worldly knowledge. It is only knowledge of the truth that is the substratum of the whole universe that can confer eternal peace.