The opening chorus is gentle and muted, especially in Ton Koopman's recording, which I found displays all his usual qualities- subtle, carefully crafted and possibly a tiny bit unexciting. There's a lovely bittersweet call-and-response figure as the upper parts sing “Ärgre dich nicht” - "do not be concerned" on a descending phrase a minor sixth apart:
(Bars 28-30, soprano and alto parts)
...which is transformed from slightly melancholy falling comfort into rising hope when the tenors and basses sing the same words in the subsequent bars:
(Bars 31-32, tenor and bass parts)
But overall, the tone of the opening chorus is summed up by the line“Der allerhoechste Licht... sich in Knechtsgestalt verhuellt”- The all-highest light hides himself in servanthood. It's that time of year when the sun of righteousness only shines for a few hours a day.
The bass aria that follows in the original version of the cantata continues the theme of comfort, but for a new, very modern sort of angst. The believer's internal doubts don't stem from a sense of his sinfulness. Here, the source of spiritual pain is Vernunft- reason, rationality; call it what you like, the spirit of the age that flowered into the Enlightenment. The soloist, accompanied by the slightly archaic sounds of a viola da gamba, calls the listener back to the old, comforting philosophy of a Lutheranism that rooted itself in familiarity with the German Bible: “Laß Vernunft dich nicht bestricken. Deinen Helfer, Jakobs Licht, Kannst du in der Schrift erblicken.”: Let reason not beguile you; you can see your your helper, the light of Jacob, in Scripture. It's a interesting message for a conservative like Bach's librettist, Salomon Franck, to write for his masters at the court at Weimar; a prod in their wealth and intellectual self-confidence. But Bach makes the message a matter of comfort, not rebuke, with another one of those beautiful calming bass arias in triple time like Mache dir, mein seele, rein at the end of the St Matthew Passion. The father of the prodigal son is reassuring, not angry.
The words for the tenor's aria betray the fact that the cantata was polished up for non-Advent use: the Leipzig version heard on all the recordings starts “Mein Heiland läßt sich merken in seinen Gnadenwerken”- my Saviour lets himself be seen in his acts of grace. But Franck's words originally started with Messias- “The Messiah lets himself be seen”, pointing towards the original and ultimate act of grace in the impending Incarnation. Personally, I think the original works slightly better, but I'm not going to argue with Bach's changes.
And this focus on the person of the Messiah leads us into the real emotional heart of the piece- a gorgeous duet for soprano and alto, locked together in a close and intimate gigue. “Laß, Seele, kein Leiden Von Jesu dich scheiden, Sei, Seele, getreu!”- Soul, let no pain separate you from Jesus, be faithful, Soul!”. Those two voices winding their way around each other might represent the unity of Christ and the soul in an eternal dance of love. Matoko Sakurada and Robin Blaze are positively ecstatic here in the recording conducted by Masaaki Suzuki with the Bach Collegium Japan. As Christmas approaches, it's always good to combine courtly dignity with a touch of red-hot passion.