What Does Joshua 4:21 Mean?

De 31:9-13. He Delivers the Law to the Priests, to Read It Every Seventh Year to the People. **9-13. And Moses wrote this law, and delivered it unto the priests--**The law thus committed to writing was either the whole book of Deuteronomy, or the important part of it contained between the twenty-seventh and thirtieth chapters. It was usual in cases of public or private contract for two copies of the engagement to be made--one to be deposited in the national archives or some secure place for reference, should occasion require. The other was to remain in the hands of the contracting parties (Jr 32:12-14). The same course was followed on this renewal of the covenant between God and Israel. Two written copies of the law were prepared, the one of which was delivered to the public representatives of Israel; namely, the priests and the elders. **the priests, ... who bare the ark of the covenant--**In all ordinary journeys, it was the common duty of the Levites to carry the ark and its furniture (Nu 4:15); but, on solemn or extraordinary occasions, that office was discharged by the priests (Jos 3:3-8; 6:6; 1Ch 15:11, 12). **all the elders of Israel--**They were assistants to the priests and overseers to take care of the preservation, rehearsal, and observance of the law.