The actually existing substance has its being or reality; it is an actual essence. Each real accident of it is likewise a reality, and has an essence, distinct from that of the substance, yet not wholly independent of the latter: it is a determination of the determinable being of the substance, affecting or modifying the latter in some way or other, and having no other _raison d’être_ than this rôle of actualizing in some specific way some receptive potentiality of the concrete substance. And since its reality is thus dependent on that of the substance which it affects, we cannot ascribe to it actual essence or being in the same sense as we ascribe this to substance, but only analogically(248) (2). Hence scholastics commonly teach that we ought to conceive an accident rather as an “entity _of an entity_,” “ens _entis_,” than as an entity simply; rather as inhering, indwelling, affecting (_in_-esse) some subject, than simply as existing itself (_esse_); as something whose essence is rather the determination, affection, modification of an essence than itself an essence proper, the term “essence” designating properly only a substance: _accidentis esse est inesse_.(249) This conception might, no doubt, if pressed too far, be inapplicable to absolute accidents, like quantity, which are something more than mere modifications of substance; but it rightly emphasizes the dependence of the reality of accident on that of substance, the non-substantial and “diminished” character of the “accident”-mode of being; it also helps to show that the “inherence” of accident in substance is a relation—of determining to determinable being—which is _sui generis_; and finally it puts us on our guard against the errors that may be, and have been, committed by conceiving accidents in the abstract and reasoning about them apart from their substances, as if they themselves were substances.