I knew all but one composer on the program (a friend of Dr. Hulin's), but I had never heard any of the works before. As I sat and listened to works by Bach and Mozart (again, that were new to me), I got to thinking about how many Bach and Mozart works I have not heard before. I also took note of the catalogue numbers next to the titles of the pieces in the program (BWV 855, K. 333) and began thinking about just what those numbers mean.