What good is a small stone?

If you skipped past the photo of the Abbey wall, I would ask you to go back to it and examine it for a few minutes.

This is not just any wall.  This is a photograph of a wall section in the Iona Abbey.  It was built during medieval times.  Notice the big rocks.  They are all different colors.  I am particularly drawn to the pink granite.  All those different rocks are from this island.  And all were brought together to make a wall.  Ultimately an Abbey.  If you are paying particular attention you noticed the tiny stones.  Why include that tiny stone?  What purpose could that tiny stone serve?  The tiny stone, which is no larger than a dime, gives added strength to the mortar in that area.  So the wall actually depends on the smallest stones to keep it standing. 

What a great way to build a church! What would the church be if we actually included everyone, regardless of who or what they are,  that is available?