Nagel argues that, because bats are apparently conscious mammals with a way of perceiving their environment entirely different from that of human beings, it is impossible to speak of "what is it like to "be" a bat "for" the bat" or, while the example of the bat is particularly illustrative, any conscious species, as each organism has a unique point of view from which no other organism can gather experience. To Nagel, the subjective character of experience implies the cognitive closure of the human mind to some facts, specifically the mental states that physical states create.