In this talk, Jacob Fisher presents his research on a history of the Buddhist discussions surrounding perceptual relativism, in India and Tibet Indian and Tibetan epistemologists have spent millennia grappling with the central philosophical questions of relativism and intersubjectivity. This talk will present my ongoing DPhil research that attempts to map a philosophical history of the discussion, by focussing on a specific Buddhist example that problematises perceptual relativism. This classic Buddhist example is the perception across world spheres of a river, which depending on the realm one belongs to, will be perceived as either blood for hungry ghosts, water for humans, or nectar for the gods. This classic example of at least three contradictory perceptions emphasises the paradox of relativism and elicits novel philosophical and epistemological solutions to this real-world problem.The story begins in India with a brief map of the chronological and philosophical developments of the example, beginning with a Pāli discourse and followed by Vinaya, Abhidharma, and Mahāyāna sources. Next, the discussion shall survey the major Tibetan exegetes of Madhyamaka philosophy over the last millennia, specifically those who use the example. Finally, we will zoom inwards to focus on a specific debate on a highly controversial interpretation of the example by Tsongkhapa (1357-1419), in which he simultaneously bolsters the importance of conventional epistemic instruments (tshad ma, pramāṇa) while at the same time undermining them through ascribing an illusory nature to all existence.