 The idea of indeterminate perception is a latecomer in Nyāya tradition. Gautama, Vātsyānana, and Uddyotakara, whose writings form the core of the early school, do not recognize an indeterminate type of perception. The tenth-century author Vācaspati introduces the notion into the system (1996: 111). Gaṅgeśa is clearly aware of this history, for he opens his discussion by echoing Vācaspati's commentary on Nyāya-sūtra 1.1.4 where, in considering the Nyāya-sūtra’s definition of perception, Vācaspati takes the two words ‘avyapadeśya’ (“non-verbal”) and ‘vyavasāyâtmaka’ (“definite”) as indicating two types of perception, indeterminate and determinate. Udayana and Gaṅgeśa follow him, but there seems to have been some dissension among later Naiyāyikas (Sibajiban Bhattacharyya 1990: 172–6).