（a^gantuka， a^gantukatva）. （1） Accidental， fortuitous， by chance. Superficial， impermanent. （2） Accidental， external taint. Defilement， especially that which was not originally present， but came from without. It is temporary and is cleaned away by true wisdom， therefore the ideograph for 'guest' 客 is used; the defilements are subtle and numerous， thus the ideograph 'dust' 尘 （chen） is used. The ideograph for 'dust' also refers to the six sensory data-fields.