It comes like the ending of the world: the sky splits open---open, so that the things behind the stars are visible. Beings formed of solid light spill down, singing music like mountains of sound, like the sea or the sky itself, so hugely it rings against the listening ears.
This is too much; the shepherds fall to the ground, sobbing into the earth, begging for mercy. They could not stand, even had they the will.
Peace, the angels sing. Peace. We bear good news, not ill.
The shepherds hear the message despite fingers stuffed desperately into ears, could not forget it if they tried. It sears itself into their memories like a brand.
At long last, scant minutes later, the sky closes again, leaving the night silent except for the sheep. And the shepherds rise like new men and go to seek the infant king.