[corey_moncure]

I think you might be referring to the Musical Offering. The Goldberg Variations were after the aria in Anna Magdalena's book.

Also, research suggests that the story of Bach dying before finishing the final fugue in Art of Fugue is inaccurate. An analysis of the paper in the extant manuscript, the tools used to draw the staff lines, and the simple realization that there is no way even Bach could have undertaken such a huge work without deriving the final combination of the fugal subjects before hand, all point to a completion in the year 1747 or 1748, but lost. The fragment that survives is likely to be a rough draft.

I wrote my senior paper in undergrad on this.

In fact the last work completed by the master is believed to be the "Et Incarnatus Est" in second (later) half of the B minor mass.