…the angel of the Lord appeared to him in a dream and said, “Joseph, son of David, do not be afraid to take Mary your wife into your home. For it is through the Holy Spirit that this child has been conceived in her. (Matthew 1)
Since Joseph was “a righteous man”, he did not know how to take it or what to do when Mary told him what had been announced to her by the angel. He did not want to do anything against God or his religion or be with anyone who might have done anything wrong. He did not want to do Mary any harm, either, so he decided to “divorce her quietly.”
So it looks like God had to do some damage control. One apparition calls for another: the angel then appeared to Joseph and was able to reassure him that he was doing the good and noble thing by continuing with his plan to take Mary as his bride. Reassured that it was God’s will, Joseph agreed to continue with plan “A”. Yet, it was no longer Plan “A” in God’s mind. Or God’s plan “A” wasn’t Joseph’s plan “A”. It was now Plan “B” for Joseph, since the son that Mary would bear would be the son of God and not his own natural human son.
Sometimes things happen in our lives that mess up our plan “A”. We perhaps think we need to change course and go a different route, perhaps the easier route. But then something happens in which God may be speaking to us to reassure us to stay with plan “A”, or to adopt his plan “A” as our plan “B”. When we have the will to do God’s will, even if it isn’t our first choice, then he blesses us and through us blesses the world. In this we pave the path for Christ to be born anew in our world.