▁the ▁New ▁World . ▁ ▁Ol mos ▁wrote ▁a ▁book , ▁unfortunately ▁lost , ▁about ▁the ▁pre - H is pan ic ▁history , ▁belief s ▁and ▁religious ▁practices ▁of ▁Mexico ▁( some ▁have ▁suggested ▁that ▁this ▁work ▁might ▁be ▁the ▁myster ious ▁Cr ónica ▁X ). ▁He ▁also ▁published ▁a ▁collection ▁of ▁H ue hu et la ht ol li , ▁moral ▁instruction ▁from ▁N ahu at l - spe aking ▁el ders ▁to ▁their ▁juni ors , ▁expressed ▁in ▁a ▁highly ▁st yl ized ▁and ▁pol ished , ▁high - register ▁language . ▁He ▁wrote ▁several ▁ser m ons ▁in ▁N ahu at l ▁which ▁have ▁surv ived . ▁ ▁But ▁he ▁is ▁best ▁known ▁for ▁his ▁Arte ▁para ▁apr ender ▁la ▁leng ua ▁mex icana , ▁completed ▁in ▁ 1 5 4 7 . ▁Although ▁it ▁was ▁based ▁on ▁his ▁own ▁and ▁others ' ▁previously ▁written ▁notes ▁about ▁Class ical ▁N ahu at l ▁grammar , ▁this ▁was ▁the ▁first ▁relatively ▁complete ▁gram mat ical ▁description ▁of ▁an ▁ind igen ous ▁language ▁of ▁the ▁New ▁World . ▁It ▁ant ed ates , ▁by ▁three ▁years , ▁the ▁first ▁gram mat ical ▁description ▁of ▁the ▁French ▁language ▁( by ▁Louis ▁Ma ig ret ▁in ▁ 1 5 5 0 .) ▁▁ ▁Ol mos ▁also ▁published ▁a ▁N ahu at l ▁V oc ab ul ary . ▁Much ▁of ▁his ▁work ▁on ▁the ▁Arte ▁and ▁the ▁V oc ab ul ary ▁was ▁done ▁in ▁H ue yt l al pan , ▁in