Johann Sebastian Bach (1685-1750) is one of the most researched composers in Western music, yet attempts to comprehend the universal personality of the man continue unabated. The earliest period of his creative life, between 1685 and 1705, presents many, as yet unsolved, problems, and what is becoming apparent is the need for a further, fresh perspective on his earliest creative development. Recent advances in document analysis techniques has pushed back the accepted dating of works usually regarded as fully mature, altering the previously accepted chronology of the point at which Bach reached full creative maturity as a composer. It is becoming increasingly apparent that this is likely to have been by 1705, expunging some of the previously accepted, but evidentially unsubstantiated or incorrect biographical positions assumed by Schweitzer and Spitta, many of which have remained largely unquestioned for over one hundred years. With specific focus on Bach’s Ohrdruf and Lüneburg periods, and with reference to source-based palaeographic research undertaken here, in particular concerning a fresh examination of the earliest available copies of BWV 768, this thesis undertakes a concise analysis of Bach’s initial compositions, with specific focus on the Chorale Partitas. It provides fresh perspectives on the creative processes which led to the composition of the extensive Lutheran Chorale Variations and defines the circumstances in which the young composer operated during his adolescent years. The final contribution in this thesis concerns fresh evidence contained in Bach’s initial compositions for keyboard, in particular through original research on the manuscript sources of BWV 768, which indicate a chronological shift to an earlier point in Bach’s life at which maturity in his keyboard pieces may now be determined.