The Ebenezer principle
When Samuel placed his stone at Mizpah and named it Ebenezer — stone of help — he wasn't making art. He was building memory. Israel had just been delivered, and Samuel knew how quickly people forget. So he set up a marker, a place to return to, a stone his children could ask about: Thus far the Lord has helped us.
We need that still. Prayers are answered and we move on. Doors open and we forget what was closed. Stones is a quiet place to gather the moments — yours, and the ones your community shares with you — so they don't slip away. Drop a stone when God meets you. Lift a prayer when something is heavy. Walk back through it later, and remember.
And he called the name of it Ebenezer, saying, Hitherto hath the Lord helped us. — 1 Samuel 7:12 (KJV)