 By contrast, Kūkai claims that detached or exoteric understanding occurs when there is a separation between knower and known, a gap that can only be bridged with the external application of linguistic categories or heuristic expressions (hōben; Sanskrit: upāya). So an exoteric philosophy, even if it knows about engagement, cannot ground its own theory in an engaged way because it depends on external relations even to express itself. It is, in effect, a theory about bodymind unity that is based only in the mind. That realization led Kūkai to argue the inherent limitation in exoteric philosophy is what gives rise to it, what in Buddhist terminology is called its mindset (jūshin).