Bach: Es ist Heil uns kommen her, BWV 9

This morning I listened to an-other Bach cantata (I've been listening to one a day since 1 February, and I'll be doing that until early August).  This time it was Es ist Heil uns kommen her, BWV 9.  In the second movement, I heard the word "Spiegel," which is German for mirror.  Because of that, I thought I knew the Biblical text used, but first I lookt up the notation so I could see the rest of the text for that section:

(notation found here)

It's not the best translation, but I translated

Wir sollten in Gesetze geh'n
Und dort als wie in einem Spiegel seh'n
Wie unsere Natur unartig sei
Und dennoch bleiben wir dabei

as

We were supposed to go into the laws
And there as in a mirror see
How our nature be ill-behaved
And nevertheless we stay with it

This wasn't the text I was expecting after I heard that "mirror."  I'd thought I would find the text from 1 Corinthians 13:12 - "For now we see in a mirror dimly, but then face to face.  Now I know in part; then I shall know fully, even as I have been fully known."

To some degree, both texts have the same contrasting ideas of seeing perfectly and seeing imperfectly.  In the cantata, there's the perfect seeing of sinful nature through the law (what "We were supposed to... see") and the imperfect seeing involved with "nevertheless we stay with it."  It's the same notion as turning a blind eye.  In the 1 Corinthians text, there's perfect seeing in knowing God "face to face" and imperfect seeing of knowing Him only partly.

So while this Bach cantata doesn't use that 1 Corinthians text, by using the same image of a mirror, it seems to hint at it.