Reasons must be expressed (hetu), examples must be given in terms of various facts (udāharaṇa), the theme must gradually be brought nearer for understanding (upanaya), and finally it must be supported by authoritative quotations from the Vedic śāstras (nigamana).
There are four chapters (adhyāyas) in the Vedānta-sūtra, and there are four divisions (pādas) in each chapter. Therefore the Vedānta-sūtra may be referred to as ṣoḍaśa-pāda, or sixteen divisions of aphorisms. The theme of each and every division is fully described in terms of five different subject matters (adhikaraṇas), which are technically called pratijñā, hetu, udāharaṇa, upanaya and nigamana. Every theme must necessarily be explained with reference to pratijñā, or a solemn declaration of the purpose of the treatise. The solemn declaration given in the beginning of the Vedānta-sūtra is athāto brahma jijñāsā, which indicates that this book was written with the solemn declaration to inquire about the Absolute Truth. Similarly, reasons must be expressed (hetu), examples must be given in terms of various facts (udāharaṇa), the theme must gradually be brought nearer for understanding (upanaya), and finally it must be supported by authoritative quotations from the Vedic śāstras (nigamana).
According to the great dictionary compiler Hemacandra, also known as Koṣakāra, Vedānta refers to the purport of the Upaniṣads and the Brāhmaṇa portion of the Vedas. Professor Apte, in his dictionary, describes the Brāhmaṇa portion of the Vedas as that portion which states the rules for employment of hymns at various sacrifices and gives detailed explanations of their origin, sometimes with lengthy illustrations in the form of legends and stories. It is distinct from the mantra portion of the Vedas. Hemacandra says that the supplement of the Vedas is called the Vedānta-sūtra. Veda means knowledge, and anta means the end. In other words, proper understanding of the ultimate purport of the Vedas is called Vedānta knowledge. Such knowledge, as given in the aphorisms of the Vedānta-sūtra, must be supported by the Upaniṣads.
According to learned scholars, there are three different sources of knowledge, which are called prasthāna-traya. According to these scholars, Vedānta is one of such sources, for it presents Vedic knowledge on the basis of logic and sound arguments. In the Bhagavad-gītā (13.5) the Lord says, brahma-sūtra-padaiś caiva hetumadbhir viniścitaiḥ: "Understanding of the ultimate goal of life is ascertained in the Brahma-sūtra by legitimate logic and argument concerning cause and effect." Therefore the Vedānta-sūtra is known as nyāya-prasthāna, the Upaniṣads are known as śruti-prasthāna, and the Gītā, Mahābhārata and Purāṇas are known as smṛti-prasthāna. All scientific knowledge of transcendence must be supported by śruti, smṛti and a sound logical basis.
