The teachers of the vedantha are oblidged to justify their special doctorines by an appeal to these three authorities ( Gita, Upanishads, Brahma Sutra) and so wrote commentaries on them expounding how the texts teach their special points of view. The Upanishads contain many different suggestions about the nature of the absolute and Its relation to the world. The Brahma Sutra is so terse and obscure that it has been used to yeild a variety of interpretations. The Gita gives a more consistent view and the task of the commentators, who wish to interpret the texts to their own ends, becomes more difficult.
Ramanuja (eleventh century A.D), in his commentary, refutes the doctorine of the unreality of the world and the path of renunciation of action. He follows the interpretation given by Yamunacharya in Githarthasngraha. Brahman, the highest reality, is Spirit, but not without attributes. He has self-conciousness with the knowledge of Himself and a concious will to create the world and bestow salvation on his creatures. He is the sum of all ideal predicates, infinite and eternal, before and above all worlds, without any second. The Vedic gods are his servants created by Him and appointed in their places to perform their ordained duties. The world is no deception or illusion but is genuine and real. The world and God are one as body and soul are one. They are a whole but at the same time unchangably different. Before creation, the world is in a potential form, undeveloped into the existing and diversified manifestations. In creation, it is developed into name and form (namarupa). By representing the world as the body of God, it is suggested that the world is not made from something alien, a second principle but is produced by the Supereme out of His own nature. God is both the instrumental and the material cause of the world. The analogy of soul and body is used to indicate the absolute dependence of the world on God even as the body is absolutely dependent on the soul. The world is not only the body of God but his remainder, isvarasyasesa, and this phrase suggests the complete dependence and contingency of the world.
All conciousness presupposes a subject and an object which is different from conciousness which is regarded by Ramanuja as a dependent substance (dharmabutadravya) capable of streaming out. The ego (jiva) is not unreal and is not extinguished in the state of liberation. The Upanishad passage, tat tvam asi, "thou art thou," means that "God is myself" even as my soul is the self of my body. God is the supporting, controlling principle of the soul, even as the soul is the supporting principle of the body. God and soul are one, not because the two are identical but because God indwells and penetrates the soul. He is the inner guide, antaryamin, who dwells deep within the soul and as such is the principle of its life. Immanence, however, is not identity. In time as well as in eternity, the creature remains distinct from the Creator.
Ramanuja develops in his commentary on the Gita a type of personal mysticism. In the secret places of the human soul, God dwells but He is unrecognized by it so long as the soul does not acquire the redeeming knowledge. We acquire this knowledge by serving God with our whole heart and soul. Perfect trust is possible only for those who are elected by divine grace. Ramanuja admits that the paths of knowledge, devotion and action are all mentioned in the Gita, but he holds that its main emphasis is on devotion. The wrectchedness of sin, the deep longing for the Divine, the intense feeling of trust and faith in God's all-conquering love, the experience of being divinely elected are stressed by him.
The Supreme is Vishnu, for Ramanuja. He is the only true god who will not share His divine honors with others. Liberation is service of and fellowship with God in Vaikutha or heaven.