▁Pope ▁Leo ▁XIII ▁wrote ▁twelve ▁en cyc lic als ▁and ▁five ▁apost ol ic ▁letters ▁on ▁the ▁Ros ary . ▁The ▁first ▁such ▁en cyc lic al ▁was ▁Sup rem i ▁apost ol atus ▁of ▁September ▁ 1 8 8 3 . ▁Most ▁were ▁issued ▁in ▁September ▁in ▁anticip ation ▁of ▁October , ▁which ▁Leo ▁would ▁have ▁dedicated ▁to ▁special ▁dev otion ▁to ▁Mary , ▁in ▁particular ▁through ▁the ▁Ros ary . ▁ ▁Sup rem i ▁apost ol atus ▁ ▁Sup rem i ▁apost ol atus ▁offic io ▁(" The ▁Supreme ▁Apost ol ic ▁Office ") ▁( comm only ▁referred ▁to ▁" On ▁Dev otion ▁of ▁the ▁Ros ary ") ▁is ▁the ▁first ▁of ▁a ▁number ▁of ▁en cyc lic als ▁of ▁Pope ▁Leo ▁XIII ▁on ▁the ▁Ros ary . ▁It ▁was ▁issued ▁on ▁September ▁ 1 , ▁ 1 8 8 3 , ▁encourag ing ▁the ▁practice . ▁ ▁Leo ▁echo ed ▁the ▁words ▁of ▁the ▁oldest ▁known ▁Marian ▁prayer ▁( known ▁in ▁the ▁Latin ▁tradition ▁as ▁the ▁“ Sub ▁Tu um ▁Pra es id ium ” ), ▁when ▁he ▁wrote , ▁“ It ▁has ▁always ▁been ▁the ▁habit ▁of ▁C athol ics ▁in ▁danger ▁and ▁in ▁trou bl ous ▁times ▁to ▁fly ▁for ▁refuge ▁to ▁Mary .” ▁He ▁then ▁gives ▁a ▁brief ▁history ▁of ▁the ▁ros ary . ▁ ▁The ▁saint ▁who ▁instit uted ▁the ▁Ros ary ▁was ▁St . ▁Domin ic ▁who ▁was ▁fighting ▁the ▁her es y ▁of ▁the ▁Al big ens ians : ▁ ▁" O ur ▁merc