  The Naiyāyikas build up in this way a model of causation, in which different causal factors have different types of causal role. The model reflects (or is reflected in) the Indian grammatical analysis of causal statements, such as “The potter throws a pot with her stick”, “The lumberjack fells a tree with her axe”, in which one distinguishes, apart from the verb designating the event, an agent (kartṛ), object (karman), instrument (karaṇa), and so on. We do not yet know, however, how to distinguish between causes and non-causes. The Manual of Reason (TS 41) provides the Navya-Nyāya answer. Given two entities, c and e,