For Martin Luther the most important thing there is in the world is the preaching of the Gospel. That is how God chooses some. It is the means that God uses to deliver the benefits of Jesus life and death and resurrection. So caught up is Luther with the proclamation of the gospel and the sermon that he states Simeon and his sermon reminds the Holy family of how special their son Jesus is. I find this particularly interesting since it was visions and visitations of Angels, a crowd of shepherd’s, Angel voices in the sky, and all the accoutrements we associate with Christmas that Mary and Joseph had lived with and yet it is a living voice of an old man speaking the gospel in a sermon that is important to this family. It was a sermon, says the Evangelist(and Luther) , that caused the child’s father and mother to marvel about the child.
The lesson is that signs and wonders are wonderful, but people, even Mary and Joseph needed the living voice of another human being to preach to them. Pastors take note.