While spending almost twenty years closely listening to Bach's more than two hundred cantatas bewildered some of my friends would decry my project and say, "They all sound alike - how can you tell them apart?" These people, sophisticated music lovers who simply did not care for the Bach vocal repertory, refused to admit they glossed over these works in a superficial way. To my ears, of course, each and every cantata had uniqueness that clearly articulated it from the rest of the pack. Yes, there were many structural similarities, and Bach's musical language is the unifying tongue, but, to say Bach's cantatas all sounded alike seemed heretical, born of inferior taste and auditory skills. Years later, when I started watching birds, I came upon the family of yellow warblers, illustrated in Roger Tory Peterson's definitive field guide. Boggled by the subtle markings which distinguish these birds, it seemed that page after page pictured the same damned bird, and I recalled my friends' remarks about Bach's vocal works.