Ave Maria: Hail the myriad Hail Marys

“Ave Maria” is quite commonly heard at both Christmas and Easter, particularly among those of Roman Catholic faith. Of course, it is Schubert’s version, and to a lesser extent, the one attributed to Bach and Gounod with which I’m familiar. Imagine my surprise and, later, my sheer delight, on learning there are, in fact, several interpretations. Why so many, and how did they come about?