The modern-day custom of performing the 'omnes generationes' section from J. S. Bach's Magnificat twice as fast as the aria "Quia respexit" has its origins in Robert Franz's vocal and orchestral editions of 1864, the details of which were discussed in his Mittheilungen of 1863. Up until that time, 'omnes generationes' was inextricably connected to "Quia respexit" and formed part of the third movement of Bach's Magnificat. Moreover, when Bach revised the score in 1733, he added adagio to the beginning of "Quia respexit . . . omnes generationes," establishing the tempo for the whole movement. In this study I show that Bach's setting of this verse is in keeping with Leipzig tradition (as evidenced by the settings of Schelle, G. M. Hoffmann, Telemann, Kuhnau, and Graupner) and with early 18thcentury compositional practice; that he interpreted the verse based on Luther's 1532 exegesis on the Magnificat; that the verse must be understood theologically, as a unit; that the change in musical texture at the words 'omnes generationes' is a rhetorical device, not "dramatic effect"; and, finally, that there is no change in tempo at the words 'omnes generationes' either in Bach's setting or in any other from this period. An understanding of the early 18th-century Magnificat tradition out of which Bach's setting derives, with the knowledge of the reception of Bach's Magnificat in the mid 19th century, should help us restore Bach's tempo adagio for the movement.