Jnana Yoga Sadhana
by Swami Sivananda
This is otherwise known by the name Nirguna Dhyana, meditation on Om, Pranava Upasana or Brahma Upasana. Purify the Chitta by doing Nishkamya Karma for one year. The effect of Chitta-Suddhi is the attainment of Viveka and Vairagya. Acquire the four qualifications or Sadhana Chatushtaya Viveka, Vairagya, Shad-Sampat and Mumukshatva. Then approach a Sat-Guru. Have Sravana, Manana and Nididhyasana. Study carefully and constantly twelve classical Upanishads and Yoga Vasishtha. Have a comprehensive and thorough understanding of the Lakshyartha or indicative (real) meaning of the Maha Vakya, Tat Tvam Asi. Then, constantly reflect over this real meaning throughout the twenty-four hours. This is Brahma Chintana or Brahma Vichara. Do not allow any worldly thoughts to enter the mind. Vedantic realisation comes not through reasoning but through constant Nididhyasana, like the analogy of Bhramarakeeta Nyaya (caterpillar and wasp). You get Tadakara, Tadrupa, Tanmaya, Tadityata, Tadleenata (oneness, identity).
No Asana is necessary for Vedantic Sadhana. You can meditate while talking, standing, sitting, lying in an easy chair, half-reclining posture, walking and eating.
Generate the Brahmakara Vritti from your Sattvic Antahkarana through the influence of reflection on the real meaning of the Maha Vakyas Aham Brahma Asmi or Tat Tvam Asi. When you try to feel that you are infinity, this Brahmakara Vritti is produced. This Vritti destroys Avidya, induces Brahma Jnana and dies by itself eventually, like Nirmal seed or strychnos potatorum which removes sediment in the water and itself settles down along with the mud and other dirty matter.