Some calendars list his birthday as March 21, not 31, but one must be careful to explain that one date (March 21) is O.S. (Old style, the Julian Calendar), the other (March 31) is N.S. (New Style, the Gregorian Calendar) and the adoption of the New Style varied across the continent depending on whether or not you were in a Catholic or Protestant country. Fortunately, birthday, aside, Bach was a musical giant for all days, the 6 Brandenburg Concertos, the Goldberg Variations, the Well-Tempered Clavier, the Toccata and Fugue in D Minor–enough to give you some notion why he is so esteemed but whose musical works gradually fell silent after his death in 1750. Who knows where he might have been without Felix Mendelssohn, who arranged to have his towering St. Matthew’s Passion played on March 11, 1829, nearly a century after it was first heard. From that day forward Bach and his works have enjoyed a special place in the pantheon of Western Composers.
Go to this website for 14 amusing musical Bach facts.