CATUSSUTRI:
The first 4 sutras of the Brahma Sutras are the famous CATUSUTRI.
1.
Inquiry into Brahman
AthAtO brahmajignyAsA
-
Then, therefore , the inquiry into Brahman.
Then (After the knowledge of the work-portion of the Vedas (karma-kAnda) and the ephemeral nature (short-lived) nature fo the results of mere work (karma) has been gained by the study of the PUrva- MImamsa),
Therefore (As the results obtained by mere work, i.e sacrifices etc., are ephemeral and limited, whereas the results of the knowledge of Brahman is eternal and infinite), t
he inquiry into Brahman (the inquiry into the
real nature of Brahman).
2.
Definition of Brahman
janmAdhyasya yataha
From whom proceed the origin etc. of this.
(Brahman is that Omniscient, Omnipotent, all-merciful Being)
from whom proceed the origin etc. (origin, sustenance and dissolution)
of this (varied and wonderfully fashioned world). **********
3.
Brahman cognizable only through the Scriptures
shAstra yOnitvAt
The scriptures (alone)
being the source of right knowledge (with respect to Brahman)
4.
Brahman the main purport of all VedAnta texts
tattu samanvayAth
But that (the scriptures alone are authority with respect to Brahman is established),
because it is the main purport (of all texts as constituting the highest aim of man).
Thus, the 4 sutras establish the necessity and possibility of the inquiry into Brahman, the definition of It, the sources of knowledge concerning It, and the supreme value of the pursuit of the knowledge in question.
************
Sri Ramanuja's definition of Brahman: From the second sutra
"That supreme Person who is the ruler of all; whose nature is antagonistic to all evil; whose purposes come true; who possesses infinite auspicious qualities such as knowledge, bliss and so on; who is omniscient, omnipotent, supremely merciful; from whom the creation, subsistence, and re-absorption of this world — with its manifold wonderful arrangements, not to be comprehended by thought, and comprising within itself the aggregate of souls from Brahma down to blades of grass, all of which experience the fruits (of their previous deeds) in definite points of space and time — proceed is Brahman"
The overview from the book:
http://ramanuja.org/sri/Web/SribhashyaOverview