In the Bṛhadāraṇyaka Upaniṣad (Book Two), the story of a debate between Gargya Balaki, the renowned philosopher, and Ajatasatru, the King of Kasi, serves as a medium to deliver the philosophical lesson that there are certain fundamental questions in philosophy for which the human mind can never find the answers—the most critical of these fundamental questions being: “What is the nature of the universe?” Here’s a summarized version of the story:
One day Gargya Balaki arrives before King Ajatasatru and says, “O King, I wish to teach you about the Brahman [the One who is the author of the universe].” Pleased at the prospect of learning something new about the Brahman, Ajatasatru replies, “I will give you a thousand cows for such a teaching.” The first explanation that Gargya offers is: “I revere as the Brahman the person in the sun.” Unimpressed by the argument, Ajatasatru replies, “Don’t talk to me about such a Brahman.” Then Gargya says, “I revere the person in the moon as the Brahman.” Ajatasatru finds this argument inadequate—the One who is the author of the universe has to be greater than the sun and the moon. Gargya then says that he reveres as the Brahman the person in the lightening—once again, Ajatasatru finds the statement inadequate. The conversation between the philosopher and the king goes on, with Gargya offering several new explanations of the Brahman: as the person in space, as the person in the wind, as the person in the fire, as the person in the waters, as the person in the mirrors, as the person in the directions, as the person in the shadows, as the person in the body [atman]—but all these explanations do not satisfy Ajatasatru. Having run out of explanations, Gargya asks Ajatasatru to take him as his student and teach him about the Brahman. Ajatasatru notes that it’s against the existing order of things for a king to be the teacher of a great philosopher, but he goes on to give his view of the Brahman—the concluding part of his statement, in the verse 2.1.20 of Bṛhadāraṇyaka Upaniṣad, is of great interest. Here’s Valerie Roebuck’s translation of the verse 2.1.20:
‘As a spider moves along its thread, as small sparks fly up from a fire, so all breaths, all worlds, all gods, all is “the truth of the truth”: the breaths are the truth, and it is the truth of them.’
Ajatasatru made a great advancement in philosophical thinking by finding inadequacy in Gargya’s every explanation of the Brahman—he formulated the philosophical view that was little known in his time: that the ultimate nature of the universe is unknowable to man. Most scholars believe that the debate between Gargya and Ajatasatru happened in the ninth century B.C.E.