In recent years, the question has been raised about Bach's birthday, and the calendar in effect at that time. Some posit that because of the shift from use of the old Julian calendar to the new Georgian calendar (in present use) the actual birthdate is March 31.
To help me out of my confusion, I wrote to Bach scholar and Harvard University professor Christoph Wolff:
I understand that recent reevaluations of the calendar have moved Bach's birthday to March 31. This, of course, messes up our long-enjoyed belief that his birthday and the spring equinox more or less coincide. Is it inappropriate to celebrated the birthday on 3/21 these days, and should one now observe the 'new' 3/31 anniversary? Or do traditions die hard? Always curious.
And I received this cordial reply:
Moving Bach's birthday is absolutely ridiculous. True, his life was actually 11 days longer because Protestant Germany adopted the Gregorian calendar in 1700 — but with the legal stipulation that all dates prior to Dec. 31, 1699, remain valid. My Bach book discusses the situation a bit in conjunction with the trip to Lüneburg. Hold on to March 21, and feel good about it!
So we'll continue to enjoy Bach's birthday on March 21. Happy birthday, J.S.!