▁School ▁of ▁Engineering ▁and ▁App lied ▁Science ▁al umn i ▁Category : St . ▁Ign ati us ▁College ▁P rep ▁al umn i ▁Category : St an ford ▁University ▁al umn i ▁Category : Univers ity ▁of ▁Notre ▁D ame ▁fac ulty ▁Category : Univers ity ▁of ▁Tennessee ▁fac ulty <0x0A> </s> ▁Pope ▁Cal li xt us ▁III ▁( 3 1 ▁December ▁ 1 3 7 8 ▁– ▁ 6 ▁August ▁ 1 4 5 8 ), ▁also ▁known ▁as ▁Alfonso ▁de ▁Borg ia ▁( ), ▁was ▁head ▁of ▁the ▁Catholic ▁Church ▁and ▁r uler ▁of ▁the ▁Pap al ▁States ▁from ▁ 8 ▁April ▁ 1 4 5 5 ▁to ▁his ▁death . ▁Borg ia ▁spent ▁his ▁early ▁career ▁as ▁a ▁professor ▁of ▁law ▁at ▁the ▁University ▁of ▁L le ida ; ▁he ▁later ▁served ▁as ▁a ▁diplom at ▁for ▁the ▁k ings ▁of ▁Arag on . ▁He ▁became ▁a ▁t utor ▁for ▁King ▁Alfonso ▁V ' s ▁il leg it imate ▁son ▁Ferdinand . ▁After ▁arr anging ▁a ▁recon c ili ation ▁between ▁Alfonso ▁and ▁Pope ▁Martin ▁V , ▁Borg ia ▁was ▁made ▁Bishop ▁of ▁Val encia . ▁In ▁ 1 4 4 4 , ▁Pope ▁Eug ene ▁IV ▁named ▁him ▁a ▁cardinal , ▁and ▁Borg ia ▁became ▁a ▁member ▁of ▁the ▁Roman ▁Cur ia . ▁During ▁the ▁Sie ge ▁of ▁Bel grade ▁( 1 4 5 6 ), ▁Cal li xt us ▁initi ated ▁the ▁custom ▁that ▁b ells ▁be ▁r ung ▁at ▁m idd ay ▁to ▁rem ind ▁the ▁faithful