John 2:11

For Jesus to "manifest his glory" means that the real truth within the Bible was revealed, to such an extent that the Lord's actual nature could be glimpsed in all its blinding brilliance. The disciples represent those who were already in a state of love and knowledge, and to "believe" means that they saw that Jesus was the Lord Himself, God incarnate. "Cana of Galilee" represents the church among the Gentiles, and signs and miracles were externally astonishing acts necessary to coax belief from the externally minded people of the day.

So while on the outside this miracle dazzled the people of Cana and convinced the disciples that Jesus was the Messiah, on the spiritual level it showed the impact His revelatory ideas would have on those people who were ready to listen and believe.