The five string quartets in this volume are generally designated as Beethoven’s ''middle quartets,'' even though stylistically they do not all build a closed unit. More than three years lie between the inception of the three quartets op. 59 (1806) and the quartet op. 74 (1809/10). In the quartets op. 59, Beethoven sprinkled several Russian folksong themes ╩ an homage to Prince Razumovsky, who had commissioned the works.This is why the pieces are often called the ''Russian Quartets.'' The next qu