Different commentators attempt to find in the Upanishads and the Brahma Sutra a single coherent doctrine, a system of thought which is free from contradictions. Bhartprapancha, who is anterior to Samkara, maintains that the selves and the physical universe are real, though not altogether different from Brahman. They are both identical with and different from Brahman, the three together constituting a unity in diversity. Ultimate reality evolves into the universal creation “Srishti” and the universe retreats into it at the time of dissolution, “Pralaya”.
The Advaita of Samkara insists on the transcendent nature of non dual Brahman and the duality of the world including “Ishvara” who presides over it. Reality is Brahman or Atman. No Prediction is possible of Brahman as prediction involves duality and Brahman is free from all duality. The world of duality is empirical or phenomenal.
The saving truth which redeems the individual from the stream of births and deaths is the recognition of his own identity with the supreme. “That thou art” is the fundamental fact of all existence. The multiplicity of the universe, the unending stream of life, is real, but only as a phenomenon.
Ramanuja qualifies the non dual philosophy so as to make the personal God supreme. While Brahman souls, and the world are all different and eternal, they are at the same time inseparable. Inseparability is not identity. Brahman is related to the others as soul to the body. They are sustained by him and subject to his control. Ramanuja says that while God exists for Himself, matter an souls exist for his sake and sub-serve his purposes.
The three together form an organic Whole. Brahman is the inspiring principle of the souls and the world. The souls are different from, but not independent of God. They are said to be only in the sense that they belong the same class. The ideal is the enjoyment of freedom and Bliss in the world of Narayana, and the means to it is either Prapatti or Bhakti. The individual souls, even when they are freed through the influence of their devotion and the grace of God, retain their separate individuality. For him and Madhva, God, the author of all grace, saves those who give to him the worship of love and faith.
For Madhva there are five eternal distinctions between (1) God and the individual soul , (2) God and matter, (3) soul and matter, (4) One soul and another, (5) one particle of matter and another. The supreme being endowed with all auspicious qualities called Vishnu and Laxmi is his power dependent on Him. Moksha is release from rebirth and residence in the abode of Narayana. Human souls are innumerable, and each of them is separate and eternal. The divine souls are destined for salvation. Those who are neither very good nor very bad are subject to samsara, and the bad go to hell. Right knowledge of God and devotion to him are the means to salvation. Without divine grace there can be no salvation.
Baladeva adopts the view of “Achintya-bhedabheda”. Difference and non-difference are positive facts of experience and yet cannot be reconciled. It is an incomprehensible synthesis of opposites. Ramanuja, Bhaskara, Nimbarka and Baladeva believe that there is change in Brahman, but not of Brahman.