Before Plato, before Laozi, before the Buddha, there were the Upanishads. In forest clearings across ancient India, long before the rise of formal philosophy or organised religion, sages sat in silence and asked the only question that ever really mattered: What am I? From that silence emerged a thunderbolt of insight—that the self and the cosmos are not two. The oldest surviving texts to declare this are not speculative essays or scriptures of belief. They are the Upanishads: bold, spare, poetic, and uncompromising in their message. Ātman is Brahman. The soul is the world. The knower is the known. And this insight, written more than two thousand years ago, remains the earliest—and perhaps the purest—expression of nonduality ever recorded.
This article sets out to show that the Upanishads are not just ancient—they are the clearest, most uncompromising voice of nonduality in human thought. By placing them in conversation with the many traditions that followed, we begin to see their singular force. In the light of comparison, their purity sharpens, like a mountain revealed when the mist lifts.
