Joshua 4:24
That all the people of the earth might know the hand of the LORD, that it is mighty: that ye might fear the LORD your God for ever. That all the people of the earth might know the hand of the LORD, that it is mighty: that ye might fear the LORD your God for ever.
The passage over the Jordan was to be remembered for this stated purpose, that every people on earth might recognize how mighty the hand of the Lord is, and that Israel might hold Him in reverent fear forever. The record of that deliverance was to be kept in memory so that its lessons would remain vivid and impressive. To that end stones of memorial were raised, and the story of the deliverance was to be told to later generations, so that all would learn the might of the Lord's power and Israel would be taught lasting reverence for Him.
Those stones were set up to preserve the deliverance and to keep the crossing from ever being forgotten. The memory was not to fade but to stay alive and impressive from one generation to the next. When children in aftertime asked what the stones meant, the people were to recount how God brought Israel across on dry land, and by that retelling the miracle was to be impressed anew upon each succeeding generation.