heyatvāvacanācca  हेयत्वावचनाच्च (I.i.8)

heyatva – rejected; avacana - absence of a special assertion; ca – also;

Since there is no special assertion that the universe has originated from something else, explained as Pradhāna in Sāṁkhya philosophy, which says that Brahman and Prakṛti are different and they both are the cause for the universe; this misconceived theory of Sāṁkhya is rejected in this aphorism. Everything originates from Brahman and all that exist is nothing but Brahman is re-emphasized because, one should not misconstrue Brahman. If Brahman is not properly taught, the student could end up knowing something else, say for example Prakṛti as Brahman. In order to avoid this confusion, this Brahma Sutra says that there is no other assertion apart from Brahman, which is explained in detail in various Upaniṣad-s. Upaniṣad-s impart the knowledge of Brahman by saying no, this is not Brahman. Bṛhadāraṇyaka Upaniṣad (II.iii.6) says, “No, not this, not this (neti neti; neti means not this). Because there is no other appropriate description to define Brahman, as nothing can describe It.”  

Consequences of not knowing Brahman could be serious as explained in Taittirīya Upaniṣad (II.5) which says, “If anyone knows that Brahman does not exist, then he himself becomes non-existent.” Such a person does not become eligible for imparting knowledge about Brahman, says Vivekachudamani (17). This verse speaks on a positive note. The verse says, “The man who discriminates between Real and unreal, whose mind is turned away from the unreal, who possesses calmness and the allied virtues and who is longing for liberation alone is considered qualified to inquire into Brahman.” What is Real? Vivekachudamani (20) answers this. “A firm conviction of the mind that Brahman is Real and the universe as it appears to our eyes is unreal. This is the discrimination between Reality and unreality. The universe appears different because of illusion known as māyā, which wrongly projects unreal universe as the true universe. This is the cause for materialism.

This Brahma Sutra says that in the absence of any other assertion about Brahman, Brahman alone is the Reality. There cannot be two Realities. If any Scripture says that Brahman is only a part of creation or part of Reality, then the Scripture advocates false teachings which will seriously hamper spiritual pursuit, as this aspirant will not be pursuing the right path. The Reality is, all that exists is Brahman and Brahman alone, which proves the point of His omnipresence.

More related articles:

Brahma Sutra - I.i.7

Brahma Sutra - I.i.9