20. The mind comes to rest through the practices of Karma, Bhakti and Jnana Yogas, not by bringing the body to rest. What makes the mind fickle and restless is desire gurgling in the mind. Manage and control desire with the intellect. Reduce the number of desires by fixing a higher ideal and working dedicatedly for it. Improve the quality of desires by substituting negative feelings with positive, loving emotions. Change the direction of desire from the transient insubstantial world to the permanent, transcendental Factor.
Then the mind will automatically look within. The mind is stilled when you see Atman in the Self by the Self. As long as the mind is outward-looking it will be agitated and edgy. Acquisition never ends and enjoyment never begins. The moment it looks within there is peace. When you discover Atman there is infinite Bliss.
21. Realisation is beyond the senses. It is a subjective becoming. Not an objective experience. You may follow objective practices but in the end it is beyond all worldly things.
This verse refers to savikalpa samadhi as it speaks of grasping by the intellect. The intellect has high penetrating power and is the last equipment to go but it has to be transcended in order to realise Atman. The intellect needs to become concentrated and one-pointed. This happens when you train the intellect with subtler realities.
Once established in Atman there is no going back. You never lose It. Development is always unidirectional. When you graduate from school to university you do not go back to school. When you learn refinement you cannot be crude or uncultured. Once you wake up from a dream you can never re-enter the same dream. Similarly once you gain Atman there is no going back into delusion.