 Despite these advantages, Nāgārjuna argues, there are some serious problems with the assumption that the epistemic instruments are self-established. First of all, if an epistemic instrument, such as visual perception, was self-established it should be able to exist independently of the existence of an object of vision. But if we then assume that it is an essential property of visual perception to see, visual perception must be able to function as its own object, as otherwise there might be no other object to be seen. This, Nāgārjuna claims, then leads to a problem already encountered in his analysis of motion. The mover and the place being moved over cannot exist simultaneously, since motion takes time; vision cannot see something that exists simultaneously with it (such as itself), since vision takes time too (MMK 3:2–3, see also Garfield 1995: 139–139).