Asambhavstu sato'nupapatteh II.3.9 (225)

But there is no origin of that which is (i.e., Brahman), on account of the impossibility (of such an origin).

Asambhavah: no origination, no creation; Tu: but; Satah: of the Sat, of the true one, eternally existing, of Brahman; Anupapatteh: as it does not stand to reason, on account of the impossibility of there being an origin of Brahman.

This Sutra states that Brahman has no origin as it is, neither proved by reasoning nor directly stated by Sruti.

The word 'tu' (but) is used in order to remove the doubt.

The opponent says that Svetasvatara Upanishad declares that Brahman is born, "Thou art born with Thy face turned to all directions" (Svet. Up. 4.3).

We cannot, as in the case of Akasa and Vayu, attribute origin to Brahman also. Brahman is not an effect like Akasa, etc. Origination of Brahman cannot be established by any method of proof.

Brahman is existence itself. It cannot be an effect, as It can have no cause. The Sruti text expressly denies that Brahman has any progenitor. "He is the cause, the Lord of the Lords of the organs and there is of Him neither progenitor nor Lord" (Svet. Up. VI.9).

Moreover it is not separated from anything else.

Neither can Sat come from Asat, as Asat has no being, for that which is not (Asat) is without a self and cannot therefore constitute a cause, because a cause is the self of its effects. The Sruti says "How can existence come out of non-existence? (Chh. Up. VI.2.2).

You cannot say that Sat comes from Sat as the relation of cause and effect cannot exist without a certain superiority on the part of the cause. The effect must have some speciality not possessed by the cause. Brahman is mere existence without any destruction.

Brahman cannot spring from that which is something particular, as this would be contrary to experience. Because we observe that particular forms are produced from what is general, as for instance, jars and pots from clay, but not that which is general is produced from particulars. Hence Brahman which is existence in general, cannot be the effect of any particular thing.

If there is no eternal First Cause, the logical fallacy of Anavastha Dosha (regressus ad infinitum) is inevitable. The non-admission of a fundamental cause (substance) would drive us to a retrogressus ad infinitum. Sruti says, "That great birthless Self is undecaying" (Bri. Up. IV.4.25).

Brahman is without any origin. According to Sruti, He alone is the True one, who exists eternally. On the supposition of the origin of Brahman, He cannot be said to be eternal. Hence such a supposition is against Sruti. It is also against reasoning, because by admitting such an origin the question of source of that origin arises; then again another source of that source and so on. Thus an argument may be continued ad infinitum without coming to a definite conclusion.

That fundamental cause - substance - which is generally acknowledged to exist, just that is our Brahman.

Therefore Brahman is not an effect but is eternal.