The philosophy of the Upaniṣads has been systematized in the Brahmasūtras (also called the Vedāntasūtras) attributed to Bādarāyaṇa. The Hindu tradition identi-fies him with the Vyāsa of the Mahā-bhārata fame.
Of the several Sanskrit commentaries on it extant today, Śaṅkara’s (A.D. 788-820) is the earliest. In the post-Śaṅkara period, several sub-commentaries were written on his Brahmasūtra-bhāṣya, necessitated by the need to further amplify certain subtle points of the Advaita philosophy or to counter the dialectical criticisms against the school. One of the most outstanding of these, is the Bhāmatī of Vācaspati Miśra (9th century A. D.) which created a new sub-school of Advaita Vedānta, known as the Bhāmatī Prasthāna.
The story goes that Vācaspati Miśra named his celebrated gloss after his wife Bhāmatī who had served him devotedly, sacrificing all the conjugal pleasures, so that he could totally apply his mind to the creative literary work.
The Bhāmatī, again, has six commentaries on it, the best-known among them being the Kalpataru of Amalānanda (13th century A. D.)
The views of the Bhāmatī school can be briefly summarised as follows: Brahman is the material cause of this world, not as the locus of avidyā or nescience but as the object of avidyās supported by the jīvas or individual selves. Māyā is only an accessory cause. Avidyā cannot abide in Brahman. It abides in the jīvas and is plural. Vācaspati advocates two kinds of avidyās: the mūlāvidyā or kāraṇāvidyā (primal nescience) and the tūlāvidyā or kāryāvidyā (derivative nescience). It is the latter that is responsible for error impressions. Also, Vācaspati seems to be more inclined towards the ‘avaccheda-vāda’ or the theory of limitation with regard to the appearance of the jīvas. Just as a pot limits the infinite sky in itself, avidyā of the individual limits Brahman and makes it appear like a jīva. Another point of importance of this work is that the mahāvākyas or great sentences (like tat tvam asi) do not produce anubhava or immediate experience. It is the mind seasoned by meditation that gives such experience.