 The terms translated ‘atom’ in Indian philosophy (aṇu, paramāṇu) refer primarily to the smallness of parts (Gangopadhyaya 1980): this notion of smallness, found in the Upanishads, was developed into atomist theories in the commentary tradition. A classic argument for atomism reasons by analogy from the fact that perceptible objects seem to be composed of parts (Chatterjee 2017). Yet, the argument ran, bodies cannot be infinitely divisible because this would lead to the paradoxical result that a mountain and a mustard seed would be equal in size. This rebuttal—closely echoed in Islamic debates—is based on the kind of paradox about summation of infinite series also found in the ancient Greek tradition (Bhaduri 1947, 55). The comparison of mountain and mustard seed was also deployed to argue that the concepts of small and large would be indistinguishable unless smallness had a defined magnitude (Gangopadhyaya 1980, 29).