tanniṣṭhasya mokṣopadeśāt तन्निष्ठस्य मोक्षोपदेशात् (I.i.7)
tanniṣṭhasya - the one who cherishes Brahman; mokṣopadeśāt – to him, liberation is taught.
This aphorism says that liberation (cessation from transmigration) is taught to the one, who believes in the Self. Why liberation is taught to the one who cherishes Brahman and not imparted to others? It is because of his faith. Brahman is the subtlest of all. Realizing Brahman is not that easy as Brahman does not appear in a particular shape and form. It cannot be seen and it can only be realized. Hence faith is paramount in realization. In Self-realization there are two aspects; one is the teaching by a Guru another is the affirmation by the disciple. At the end of confident and true affirmation realization happens. The first aspect is teaching. Guru says to his disciple, “You are Brahman”. The disciple carefully analyses this teaching using his antaḥkaraṇa (mind, intellect, consciousness and ego) and finally realizes that he is That. Now he truthfully affirms, “I am That”.
Chāndogya Upaniṣad (VI.viii.7) says, “That which is the subtlest of all this is the Truth. It is the Self. You are That (Brahman).” This is the teaching of a father (Uddālaka Āruṇi) to his son Śvetaketu. But Śvetaketu is not able to fully understand his father’s teachings. He seeks explanation from his father repeatedly and the father uses different explanations to teach him. Why Brahman is called as That, which refers to an insentient (devoid of consciousness and feeling) thing. When a sentient being is told (the disciple) that he is That, how can the sentient being think that he is insentient? This argument arises because of the usage “tat tvam asi” where tat means That. Why it is not said “You are Him” or “You are Her”? It is because Brahman has no gender. It is neither a male nor a female nor a eunuch? Let us take the seed of a tree? What gender is the seed? How to call this seed, he or she or it? Since it has no gender, it is called as it only. But how important is the seed for the growth of the tree? Seed alone is important for the existence of the tree. Similarly, Brahman is the seed, who is without gender, neither sentient nor insentient, yet the universe originates from It, like the tree originating from the seed. Seed is tiny, whereas the tree is huge. Similarly, Brahman is subtle and tiny (smaller than an atom, says Kaṭha Upaniṣad) and the same Brahman manifests as the universe (bigger than the biggest says Kaṭha Upaniṣad). It is the seed that grows into a tree; similarly it is Brahman which manifests as the universe. Śvetāśvatara Upaniṣad (III.9) says, “There is nothing better or worse than this Self. Similarly, there is nothing smaller or bigger than this Self.” The same Upaniṣad further says (III.10), “That Self is without form…Those who know this Truth become immortal (cessation from transmigration) and others suffer.”
But what is the need to know Brahman? Knowing Brahman is only for the purpose getting relief from the pains of births and deaths. How one is relieved from the pains of transmigration? This is answered in Chāndogya Upaniṣad (VI.xiv.2) which says, “A person who gets a Guru attains knowledge about the Self (through teaching). He (the disciple) continues to live as long as his body is there (because of his karmas) and once his body dies (after exhausting all his karmic impressions by experiencing them), he is liberated and becomes one with the Self.” In the interim period, he can also impart knowledge of the Self to others.
In this sūtra, more emphasis is given to the concept of Guru, a Self-realized teacher. Otherwise, one’s spiritual journey is like a blind person leading another blind person out of a thick forest. Both of them will not be able to get out of the forest and instead they go deeper into the forest, unable to find a solution to come out of the forest. Similarly, if one does not have the right Guru, not only the aspirant falls, but also the teacher.