When children are small and are just learning how to eat from a spoon, parents involuntarily open their mouths even as the baby opens his or her mouth. It's quite comical to see. Pastors who get to sit up front in church each week often get to see a similar spectacle whenever young children participate in a church service or Christmas program. When a son or daughter is up front speaking various lines, it's not uncommon to be able to look out into the congregation only to see the tyke's mom or dad on the edge of a pew, mouthing the words right along with the child! As a parent, you can't help it!
I suspect that seen the right way, something similar happens in Luke 1. The whole cosmos, all the hosts of heaven from the archangel Gabriel on down, are holding their collective breath and sitting on the edges of their seats. All eyes and ears are trained on one little girl, perhaps no more than twelve or thirteen years of age. She's about to get the shock of a lifetime, but what will she say in response? What will her answer be? Will she get it right? As Frederick Buechner once put it, Mary was probably too dazzled to notice, but maybe just beneath his wings and bright garments even Gabriel was trembling a little in nervous anticipation at how this encounter was going to go.
In the end, as we all know, it went just fine, and the hosts of heaven must surely have heaved a collective sigh of relief! The long-awaited plan of salvaging this fallen creation was now really moving forward! After ages of waiting, a mother had been chosen to become the bearer of the very Son of God himself. Within a year that little baby would be born in Bethlehem, and the salvation of the galaxies would be off and running (or at least off and crawling initially!).