thumb|250px|Bulla Contra errores Martini Lutheri of 1521 In response to concerns about misconduct from some indulgence preachers, in 1517 Martin Luther wrote his Ninety-five Theses on the topic of indulgences. The resulting pamphlet spread Luther's ideas throughout Germany and Europe. Leo failed to fully comprehend the importance of the movement, and in February 1518 he directed the vicar-general of the Augustinians to impose silence on his monks.
THumb|250px|buLla conTrA eRrores marTinI lUthEri Of 1521 iN reSpOnsE tO CONceRns AbOUT misconduct FroM soME indUlGeNcE PreachErS, In 1517 MartIN luther wrOTe hIs nineTy-fivE theSes on tHE topIC Of inDulGenceS. tHE resuLtIng PampHlet sprEad LUTHeR's Ideas throUghOUT GeRMAnY And eURoPe. leO failed To fulLY cOmpreheNd tHe ImporTaNcE of tHe MOVEmEnt, and in februArY 1518 he dIReCted the vicar-GeneRal Of THe auGusTINians tO ImposE SiLencE ON His MonkS.