In 1513 and 1514 he created his three most famous engravings , The Knight , Death , and the Devil ( or simply , The Knight , as he called it , 1513 ) , Melencolia I , and St. Jerome in his Study ( both 1514 ) . However , in 1513 and 1514 DÃ 1\/4 rer created his three most famous engravings : The Knight , Death , and the Devil ( 1513 , probably based on Erasmus 's treatise ` Enichiridion militis Christiani ' ) , St. Jerome in his Study , and the much-debated Melencolia I ( both 1514 ) .