The Vedic evidence is very chronologized in the Vedānta-sūtra. He especially mentioned brahma-sūtra-padaiḥ. Brahma-sūtra means Vedānta-sūtra. Vedānta-sūtra means the summary of all Vedic knowledge. The Vedic knowledge is given in codes. That is called Brahma-sūtra. Sūtra means code, and Brahman means the Supreme Absolute Truth. Understanding of the Absolute Truth in code words, and the explanation.
A code word requires explanation. Just like in business circle there is Bentley's code. So for business facility, for saving expenditure, the telegraphic codes are there. So one who does not know what is this code, but he can refer to the book. The explanation is there: "This code means this wording." Similarly, Brahma-sūtra means the whole Vedic knowledge is given in codes. Brahma-sūtra-padaiś caiva hetumadbhiḥ (BG 13.5). It is called nyāya-prasthāna. Nyāya-prasthāna . . . nyāya means logic. Nyāya means . . . there are three kinds of authorities: śruti-prasthāna, smṛti-prasthāna and nyāya-prasthāna. So the Brahma-sūtra is nyāya-prasthāna, very logically, very logically given.
Just like in the first code in the Brahma-sūtra is athāto brahma jijñāsā. Brahma-jijñāsā: to inquire about the Absolute. The jijñāsā means inquiry. In the cats' and dogs' life the inquiry is, "Where is food? Where is shelter? Where is sex?" and "Where is defense?" only these four inquiries. The cats and dogs, they are busy, "Where is food? Find out some food." The pig is finding out, "Where is stool? Where is stool?"