  Noticing something coiled up in the corner of the room, I perceive it to be a piece of rope. Looking out of the window, I see that the sky is blue and see also, perhaps, the blueness of the sky. I see too that the air is cold, and that there is nobody on the street. What do all these experiences have in common, in virtue of which they are all acts of perception? The Manual of Reason (TS 46) gives the classical Nyāya answer: