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The first group of texts distinguishes Brahman from the world and the individual selves. In a way it emphasizes the transcendent character of Brahman. The second group of texts declares Brahman to be the inner self of all entities. Neither the individual self nor the world can exist by itself.
They are inseparably connected with Brahman as his body, and thus are controlled by him. These texts teach duality in so far as distinction is made between body and self, and unity in so far as the self, the substantive element, predominates over and controls the body, its attribute. The last group of texts aim at proclaiming the non-dual character of Brahman who alone constitutes the ultimate Reality. The self and the world, though distinct from each other and real, have a different value. They only exist as a mode or attribute of Brahman. They are comprehended in the reality of Brahman. They exist because Brahman exists.
On this principle of interpretation, Sri Ramanujan recognizes that the passages declaring distinction between Brahman, the world and the self, and those affirming Brahman to be the same in the causal as well as effected aspects, do not in any way contradict the mediating passages which declare that the individual selves and the world form the body of Brahman, and they in their causal state do not admit the distinction of names and forms while in the effected state they possess distinct character.
The notion of unity may be illustrated by the example, "A purple robe." Here purpleness is quite different from robe. The latter is a substance while the former is an attribute. This integral and essential relation is not found in the case of a man wearing a wrist-watch. If the former relation is inseparable (apthaksiddhi), the latter is separable and external. A word signifying attribute does not stop after denoting the usual meaning, but extends till it reaches the substantive. This is the true significance of an attribute. The individual selves and the world constitute the body of Brahman who is their inner self. Brahman is the integral principle without whom neither the self nor the world can exist. Hence all names finally denote him.
The way in which Sri Ramanuja interprets the famous text, 'That thou art' (tat tvam asi) is unique. This is done by means of co-ordinate predication (s^am^an^adhik^araya). In a co-ordinate predication the identity of the substantive should not be established through the rejection of the natural significance of co-ordinate terms. The identical import of terms taken in their natural signification should be brought out. The Mahabhashya of Patanjali defines co-ordinate predication thus: "The signification of an identical entity by several terms which are applied to that entity on different grounds is co-ordinate predication." 9 In such a proposition the attributes not only should be distinct from each other but also different from the substance, though inseparable from it.
In the illustration of a "purple robe", the basic substance is one and the same, though "purpleness" and "robustness" are different from it as well as from each other. That is how the unity of a "purple robe" is established. In the co-ordinate predication asserting identity between "that" and "thou", Brahman himself with the self as his mode, having the self as his body, is pointed out.
The term "thou" which usually stands for the self here stands for Brahman ("that") who is the in dweller of the self and of whom the self is the mode as a constituent of his body. The term "thou" does not mean the physical body or the individual self. Since Brahman has interpenetrated all matter and self, "thou" signifies Brahman in the ultimate analysis. The term "that" signifies Brahman himself as the ground of the universe and the soul of all individual selves.
Hence in the identity of "that" and "thou" there is no rejection of the specific connotation of the co-ordinate terms. The upshot of the dictum is that the individual selves and the world, which are distinct and real attributes, are comprehended in Brahman. Brahman as the inner self of the jiva and Brahman as the ground of the universe are one. The central principle is that whatever exists as an attribute of a substance, that being inseparable from the substance is one with that substance.
Thus Sri Ramanuja upholds all the three streams of thoughts in the Upanishads, namely, unity, plurality and both. He himself clinches the argument:
We uphold unity because Brahman alone exists with all other entities as his modes. We uphold both unity and plurality, as the one Brahman himself has all the physical and spiritual entities as his modes and thus exists qualified by a plurality. We uphold plurality as the three entities - the individual selves, the world and the supreme Lord - are mutually distinct in their substantive nature and attributes and there is no mutual transposition of their characteristicsERQ3FCHKA2WB