 Only Cārvāka hints at the causal closure of the physical world, and the four models of causation entertained in Indian philosophy allows interactions between matter and consciousness, material particles and mathematical entities, non-living and living beings, accumulated merits and demerits of past actions and present events, and so on. This, however, should not lead one to think that Indian thinkers admit transgression of the barrier between the natural and the supernatural. On the contrary, they establish their own criteria of demarcation and in doing so legitimize the admission of various kinds of entities in the ‘natural world’.