When I lived in San Antonio there was a lot of building going on and limestone was used in building a lot. It was everywhere, Dig a hole and chances are – limestone.
I had a chance to watch some of the stone masons in action. These guys were very fast in their work. As they built a wall, or a stone facing on a building, They would take a stone from the pile of stones, Look it over to see where it would fit in any of the open spaces, And bam, place it and move on to the next stone. Every so often they would take their hammer and give a chip here or there, But rarely would they cast a stone aside. They were so efficient in their work, They could spot weakness in a stone with one glance. They knew a defective stone almost instinctively - The cast off stones were not given a second look.
In the time of Jesus, stone was the building material. Builders would start with the perfectly square cut cornerstone, Set it just right, and build out from that point. If the stone was a little off, the building would be crooked. So the builders look very carefully at that first stone
Because if they pick the wrong stone, At some point they will have to tear down the whole thing.
So we see in psalm 118:2 that Jesus didn’t look like what was expected. And so he was set aside, by the Jewish authorities of the day.
He was overlooked in the building of their spirituality.
But God, not only approves of Jesus, but values him, He picks him up out of the cast off pile – and places him in a place of honor. Jesus is the cornerstone – in other words what we are to build our life off of , Just like the ancient stone masons.