Then Samuel took a stone and set it up between Mizpah and Shen. He named it Ebenezer, saying, "Thus far has the LORD helped us." 
1 Samuel 7:12

Throughout the Scriptures we read of several people designating stones as monuments for remembering the deliverance or encountering of God in that place.

If you recall Jacob had set up a stone pillar at the place where God had talked with him and called it Bethel (Genesis 35:14,15) and Joshua had set up the twelve stones that had been in the middle of the Jordan at the spot where the priests who carried the ark of the covenant had stood. (Joshua 4:9). King David confessed several times that the Lord was his rock of salvation (Psalm 18:2).

Here Prophet Samuel sets up a monument to remember the return of the Ark of the Lord and names it Ebenezer which means "Thus far the Lord has helped us".

Now how about us? Do we have monuments that remind us of God's grace in our lives? Sure why not, birthdays, anniversaries, years of experience, number of children, all stand as reminders of God's grace in our lives.

But then if these are not enough reminders and/or if we would somehow forget what the Lord has done thus far, we might as well put up some monument as reminders. Let us praise the Lord for helping us thus far!