▁of ▁natural ▁law ▁introduced ▁by ▁Albert us ▁Magn us ▁and ▁elabor ated ▁by ▁Thomas ▁Aqu inas , ▁particularly ▁in ▁his ▁Sum ma ▁The ologia e , ▁and ▁often ▁as ▁filtered ▁through ▁the ▁School ▁of ▁Sal aman ca . ▁This ▁view ▁is ▁also ▁shared ▁by ▁some ▁Protest ants , ▁and ▁was ▁del ine ated ▁by ▁Ang lic an ▁writer ▁C . ▁S . ▁Lewis ▁in ▁his ▁works ▁M ere ▁Christian ity ▁and ▁The ▁Ab ol ition ▁of ▁Man . ▁ ▁The ▁Catholic ▁Church ▁understand s ▁human ▁be ings ▁to ▁consist ▁of ▁body ▁and ▁mind , ▁the ▁physical ▁and ▁the ▁non - phys ical ▁( or ▁soul ▁perhaps ), ▁and ▁that ▁the ▁two ▁are ▁in ext ric ably ▁linked . ▁Hum ans ▁are ▁capable ▁of ▁disc ern ing ▁the ▁difference ▁between ▁good ▁and ▁evil ▁because ▁they ▁have ▁a ▁conscience . ▁There ▁are ▁many ▁manifest ations ▁of ▁the ▁good ▁that ▁we ▁can ▁purs ue . ▁Some , ▁like ▁pro cre ation , ▁are ▁common ▁to ▁other ▁animals , ▁while ▁others , ▁like ▁the ▁purs uit ▁of ▁truth , ▁are ▁incl in ations ▁peculiar ▁to ▁the ▁capac ities ▁of ▁human ▁be ings . ▁ ▁To ▁know ▁what ▁is ▁right , ▁one ▁must ▁use ▁one ' s ▁reason ▁and ▁apply ▁it ▁to ▁Thomas ▁Aqu inas ' ▁pre cept s . ▁This ▁reason ▁is ▁believed ▁to ▁be ▁emb od ied , ▁in ▁its ▁most ▁abstract ▁form , ▁in ▁the ▁concept ▁of ▁a ▁primary ▁pre cept : ▁" Good ▁is ▁to ▁be ▁sought , ▁evil ▁avoided ." ▁St . ▁Thomas