Overtures belong at the beginning, introducing what is to come. So why is one found at Variation 16 of the giant Goldberg Aria and Variations? 

Well, it is the beginning, but of the second half of 30 variations. Variation 15 takes us into fear and anguish with a mirrored canon in the (unheard of) key of G minor. After 45 minutes of bright G major since the opening aria, this change into the parallel minor key is stark, but not as stark and bare as the open fifth ending: a lone D string. Then follows a pause (in this performance by Jean Rondeau) of fully 35 seconds.

We start fresh, renewed with the joy of G major after this pause which literally divides the performance in half. The French "Ouverture" is a new beginning, replete with bright and shimmering baroque ornamentation. And yet it fits in the mold of the harmonic structure of the original Aria. While we think that there are beautiful performances of the Goldberg Variations on the modern piano, we lament the limitations of the low end of our big new instrument. Of all the 30 plus the Aria, this variation is the one which must be heard on the instrument for which it was intended -- harpsichord. 

Aria mit 30 Veränderungen (Goldberg Variations) BWV 988: Jean Rondeau, Netherlands Bach Society