Ever since Indians of the Vedic era created poetry, prose and philosophy and recorded them for posterity in the Samhitas, Brahmanas and Upanishads, a profound and perennial question challenged them. A question whose answers remain to be perfectly grasped and applied by the modern world, despite all its advancements. What is valid knowledge? What is its true source? As the centuries rolled by in India, many a great philosopher tried to answer this. Let us hear what each of them had to say, sticking to chronology wherever possible. Let us see if their story of debate, disagreement and yet a subtle underlying similarity has anything to teach us. At the very earliest time, the Vedic philosophers reigned supreme in India’s intellectual sphere. They held debates among themselves, as we see in stories about the courts of Janaka and Ajatashatru. But it was always on the details of their system and not on epistemology. In their monopoly of philosophy, they held that the Monism of the U...