William H. Scheide (1914-2014) who was considered the dean of American Bach scholarship was a graduate of Princeton University and later received a masters degree in musicology from Columbia University. He was also an accomplished pianist and organist. In 1946, he founded the Bach Aria Group, a New York-based performing ensemble that he directed for 35 years. Scheide was a charter member of the American Bach Society, which was founded in 1971 - initially as the American Chapter of the German Neue Bachgesellschaft; he was later made an honorary member of both societies. In 1990, he took steps to encourage the work of younger Bach scholars by establishing endowments for the William H. Scheide Prize and the Scheide Research Grant. Over several decades of his life, Scheide added to his grandfathers and fathers collection of bibliophile rarities precious autographs by Bach, among other important music manuscripts and prints of works by Mozart, Beethoven, Wagner and numerous other composers. In 1953, he acquired the magnificent oil portrait of Bach by Elias Gottlob Haussmann (Leipzig, 1748), which is the best-preserved original likeness of the composer. For well over half a century, Bach himself as it were watched over him and encouraged him to search, research and communicate, to engage his scholarly intellect and to set a lofty standard for critical inquiry. For Scheide the present study became almost a lifetime companion. Inspired by Alfred Drrs groundbreaking study on the chronology of Johann Sebastian Bachs Leipzig vocal works (1957), he recognized its enormous potential for reconstructing Bachs artistic choices, his dramatic plan and stylistic development. From week to week he followed Bachs arduous task of his first Leipzig cantata cycle (1723/24) in his own highly meticulous and empathic way, deeply immersing himself in the musical world of the composer. Scheides opus magnum is presented here in a reduced and revised version. Although Bach scholarship has significantly progressed in the past decades, the initial idea that the author developed in his manuscript the harmonization of source scholarship and his intimate knowledge of the scores is methodically still valid and has by no means been superseded.