"If it had been a snake, it would have bit me." This ol' saying that I heard growing up was used when you were looking for something and it was right under your nose the whole time but you just couldn't see it. Usually you couldn't see it because you were careless, in a hurry, or not concentrating on what you were doing.
So, often as spiritual seekers, we get frustrated at missing the leading of God as we try to discern his will in the important decisions of our lives. Yet his truth is right under our noses: "if it had been a snake, it would have bit us." The Jewish leadership rejected God's Son, their stone of salvation, because they were not looking for a Messiah who was like Jesus. He didn't fit their idea of a Savior. In their carelessness and hardness of heart, they rejected the very stone on which their salvation should have been built. Unfortunately we can do the same thing when we try to fit God's will for us and Jesus' leading of us into our plan rather than trying to discern his will. Let's not stumble on the stone God provided for our salvation!