I mentioned this in a sister comment, but I will add: * Schenkerian analysis is probably the modern method of looking at Bach. A sister comment also indicates

I mentioned this in a sister comment, but I will add: * Schenkerian analysis is probably the modern method of looking at Bach. A sister comment also indicates that Schenker was a controversial figure (he was a German fascist), but I believe the follow-ups from other theorists on his methods are the modern ones to use for analysis. * Analyzing otherwise in the context of counterpoint and intervals - see Gradus ad Parnassum and Kennan's book on counterpoint.