This is meditation on Nirguna Brahman. This is Ahamgraha Upasana. This is meditation on OM. This is meditation on an abstract idea. Sit in Padmasana. Repeat OM mentally. Keep the meaning of OM always in the mind. Feel that you are the All-pervading, Infinite Light. Feel that you are the "Suddha-Sat-Chit-Ananda, Vyapaka Atman, Nitya Suddha Buddha Mukta, eternally free Brahman." Feel you are Chaitanya. Feel that you are the "Akhanda Paripurna, Ekarasa, Santa, Infinite, Eternal, Unchanging Existence." Every atom, every molecule, every nerve, vein, artery should powerfully vibrate with these ideas. Lip repetition of OM will not produce much benefit. It should be through heart, head and soul. Your whole soul should feel that you are the subtle, all-pervading Intelligence. This feeling should be kept up continuously.
Negate the body-idea when you repeat OM mentally. When you chant OM, feel:
Infinity I am OM OM OM
All Light I am OM OM OM
All Joy I am OM OM OM
All Glory I am OM OM OM
All Power I am OM OM OM
All Knowledge I am OM OM OM
All Ananda I am OM OM OM
Meditate on the above ideas constantly. Constant effort with zeal and enthusiasm is indispensable. Repeat mentally the above ideas incessantly. You will realise. You will have Atma-Darshan within two or three years.
Will and Manana are two important factors which play a conspicuous part in Nirguna meditation or Vedantic Sadhana. Manana is preceded by Sravana or hearing of Srutis and followed by Nididhyasana of a constant nature with zeal and enthusiasm. Nididhyasana is profound meditation. Sakshatkara or Aparoksha realisation follows Nididhyasana. Just as the drop of water when dropped on a hot iron is absorbed by the hot iron, so also the mind and the Abhasa Chaitanya (reflected consciousness) become absorbed in Brahman. The balance left is Chinmatra or Chaitanya Matra (Consiciousness-Absolute). Sravana, Manana and Nididhyasana of the Vedantic Sadhana correspond to Dharana, Dhyana and Samadhi of Raja Yoga of Patanjali Maharshi.
By worship and meditation or Japa of Mantras, the mind is actually shaped into the form of the object of worship and is made pure for the time being through the purity of the object (namely, Ishta Devata). By continual practice (Abhyasa), the mind becomes full of the object to the exclusion of all else, steady in its purity and does not wander into impurity. So long as the mind exists it must have an object and the object of Sadhana is to present it with a pure one.
The sound repeatedly and harmoniously uttered in Japa of Mantra must create or project into perception the corresponding thing, Devata. The Mantras gather creative momentum by repetition through the force of Samskaras.
In Samadhi, the mind loses its own consciousness and becomes identified with the object of meditation (Tadakara Tadrupa). The meditator and meditated, the worshipper and worshipped, the thinker and the thought become one. The subject and the object, Aham and Idam (I and this), Drik and Drisya (seer and seen), the experiencer and the experienced become one. Prakasa and Vimarsa get blended into one. Unity, identity, homogeneity, oneness, sameness refer to Nirvikalpa Samadhi.
There are two kinds of Nirvikalpa Samadhi, viz., one in which the Jnani sees the whole world within himself as a movement of ideas, as a mode of being or a mode of his own existence, like Brahman, by resting in Brahman (Svarupa Visranti). Brahman sees the world within Himself as His own Sankalpa or Vivarta. So does a Jnani also. This is the highest state of realisation as in the case of Lord Krishna, Lord Dattatreya, Sri Sankara, Jnanadev and others.
"The self, harmonised by Yoga, seeth the Self abiding in all beings, all beings in the Self; everywhere he seeth the same." (Gita VI-29).
But in the case of the man who has no realisation, he sees the world as something outside, different and independent. This is due to Avidya.
In the second variety, the world vanishes from view and the Jnani rests on Suddha Nirguna Brahman, according to Rajju-Sarpa Nyaya (analogy of snake in the rope). When a Raja Yogi gives up his Savikalpa Samadhi, he meets the Jnani in Nirguna Brahman through Brahmakara Vritti.
There is a living universal Power or Intelligence that underlies at the back of all these names and forms. Meditate on this Power or Intelligence which is formless. This will form an elementary Nirguna meditation without any form. This will lead to the realisation of the Absolute, Nirguna, Nirakara consciousness eventually.
Sit in Padmasana. Concentrate on the air. This will lead to the realisation of the nameless and formless Brahman, the one living Truth.
Imagine that there is a Parama, Ananta, Akhanda Jyotis (Supreme, Infinite effulgence) hidden behind all the phenomena with an effulgence that is tantamount to the blaze of crores of suns. Meditate on that. This is also another form of Nirguna meditation.
Concentrate and meditate on the expansive sky. This is also another kind of Nirguna, Nirakara meditation. By the previous methods in concentration the mind will stop thinking of finite forms. It will slowly begin to melt in the ocean of Peace, as it is deprived of its contents, viz., forms of various sorts. It will become subtler and subtler also.
Nirguna meditation is abstract meditation on Nirguna Brahman. Repeat OM mentally with Bhava (feeling). Associate the ideas of Sat-Chit-Ananda-Purity, Perfection, "All Joy I am: All Bliss I am: I am Svarupa: Asangoham-I am unattached: Kevaloham-I am alone: Akhanda-Eka-Rasa- Chinmatroham."