Proverbs 16:9 says, "In their hearts humans plan their course, but the Lord establishes their steps." Joseph and Mary would have known that verse from their childhood training. They knew it was true but I'm thinking the proverb took on a new meaning as they reflected on the events surrounding their engagement and eventual marriage. They had plans, but God had other plans. And God's plans changed the world and offered a blessing for "all the nations."