Combining the color of the alto voice with the plangent sound of an "alto oboe" (the hautbois d'amour or oboe d'amore) must also have been a delight to Bach, as he wrote many arias for the two. It is our good fortune that these explorations in the alto register are preserved on paper, so we can savor them again today.

The hautbois d'amour, with its poetic name and bulb-bell, must always have aroused curio-sity. The instrument appeared quite suddenly in the mid-1710s, enjoyed a brief but dazzling career, and had virtually disappeared by Mozart's time. Although the name "oboe d'amore" seems to have become popular nowadays, in its heyday the instrument was normally known by its French name - and this, despite the fact that it was exclusively a German phenomenon; there is good reason, in fact, to think the hautbois d'amour was invented in Leipzig (most of its earliest repertoire was written by composers closely tied to Leipzig, and many surviving instruments were made there).

By the time Bach first wrote for it in February 1723 for his audition at Leipzig, the hautbois d'amour was much in vogue; his competitors for the post (Telemann and Graupner) had already been writing for the new instrument for half a decade.
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