Vaiśeşikas are realist philosophers of classical India. They admit time (kāla) as a ubiquitous real substance. In this paper, our aim is to discuss such a determination of time following sixth century Vaiśeşika scholar Praśastapāda and a few of his interpreters, Vyomaśivācārya and Udayanācārya. This paper is an effort to state realist philosophers’ understanding of time and also to highlight how in classical Indian tradition, interpretations paved the way for proving the reality of time. The application of logical methods by (...) the Vaiśeşika interpreters is also worth studying. These methods show the internal development occurring in the system of Vaiśeşika. Praśastapāda stated different notions like priority etc. (paratvādi) as the linga or hetu of kāla. Vyomaśiva and Udayana have established this statement of Praśastapāda as the lakşaņa of kāla by virtue of different forms of inference. (shrink)