This is My name forever; and this is My memorial to all generations.
God wants us to have memorials so we won’t forget. He preserved Noah and his family through the flood and then gave them the memorial of the rainbow. From that day on, we can look into the sky at a rainbow and remember how God delivered Noah and has promised never again to destroy the earth by water.
God gave the Israelites the ark of the covenant that they carried with them. Inside the ark were the Law that God had given to Moses on Mt. Sinai, the stone tablets to remember when God had given His people a code of conduct by which to live, and a little jar. The Bible says that inside that jar was some of the manna God had fed the people during their forty years of wandering. Why manna? It was another memorial to the fact that God can feed people right there in the desert where there were no restaurants.
The Lord was wise. He instituted memorials. Why? Because we have a tendency to forget. We need to remember that we have a God who has worked in the past, and because He has worked in the past, He is willing to work in the present.
 Jeremiah, D. (2002). Sanctuary: finding moments of refuge in the presence of God (p. 165). Nashville, TN: Integrity Publishers.