▁three ▁sub - sch ools ▁have ▁developed , ▁of ▁which ▁long d é ▁is ▁one . ▁The ▁other ▁two ▁divisions ▁or ▁schools ▁are ▁sem de ▁and ▁men ng ag de . ▁▁ ▁Pen or ▁R in po che ▁refers ▁to ▁long d é ▁ ▁as ▁the ▁Cent red ness ▁School ▁and ▁is ▁attributed ▁to ▁Dor je ▁Z ampa , ▁Sri ▁Sing ha ▁and ▁V airo ts ana ' s ▁line age . ▁ ▁Background ▁These ▁three ▁divisions ▁were ▁introduced ▁by ▁the ▁Buddh ist ▁scholar ▁Ma ñ ju ś r ī mit ra . ▁As ▁D z og chen ▁texts , ▁the ▁texts ▁of ▁all ▁three ▁divisions ▁are ▁concerned ▁with ▁the ▁basic ▁prim ord ial ▁state ; ▁the ▁nature ▁of ▁mind - its elf ▁( which ▁is ▁contrast ed ▁with ▁normal ▁conscious ▁mind ). ▁They ▁are ▁related ▁to ▁the ▁" Three ▁Stat ements " ▁() ▁of ▁Gar ab ▁Dor je . ▁ ▁It ▁is ▁important ▁to ▁note ▁that ▁the ▁three ▁series ▁do ▁not ▁represent ▁different ▁schools ▁of ▁D z og chen ▁practice ▁as ▁much ▁as ▁different ▁approaches ▁to ▁the ▁same ▁goal , ▁that ▁being ▁the ▁basic , ▁natural , ▁and ▁prim ord ial ▁state . ▁ ▁As ▁is ▁common ▁throughout ▁much ▁Buddh ist ▁literature , ▁Tib et an ▁Buddh ism ▁in ▁particular , ▁grad ations ▁in ▁the ▁fac ult ies ▁of ▁pract ition ers ▁are ▁also ▁as cribed ▁to ▁the ▁three ▁divisions , ▁they ▁being ▁seen ▁as ▁appropriate ▁for ▁pract ition ers ▁of ▁low , ▁m idd ling , ▁and ▁high ▁fac ult ies