The Interpretation of "深则厉,浅则揭"in the Book of Songs

After a comprehensive survey from various angles of language, character, culture and the history of bridge development, the author points out that Li厉(?)are stones set in water, which one can step on to cross a river.Jie(揭)refers to ones crossing a river with clothing highly lifted by hand or on head . From the history of bridge development, Li(厉)is the predecessor of bridge. 深则厉,浅则揭means that in deep water one should cross the river with clothing highly lifted,but he does it by stepping on stones; in shallow water one should step on stones to cross the river , but he does it with the clothing lifted.