Deep trouble- Aus der Tiefe rufe ich – Cantata for a time of Penitence.

We're still in the Lenten desert, a series of cantata-less weeks when Bach's major cantata cycles temporarily dry up. Luckily, there are some orphaned week-less cantatas too, written for unknown events and with no obvious place in the calendar. This one is special; written around 1707-8 when Bach was barely twenty-two years old in his brief nine-month stay as organist of the church of St Blaise in Muhlhausen. Some people suggest it was written for a penitential service after a devastating church fire.

It's also one of the first cantatas Bach ever wrote- and a fascinating contrast to the later Leipzig cycles. All generalisations about Bach's music are to some extent wrong (apart from “it's all good”); but I'll risk it. In the later cantatas I've heard, I feel the structure is often driven by an emotional and didactic journey. They're like sermons; they lead the listener through. Earlier movements set out the spiritual problem; later ones show the resolution. And this emotional journey means you can't go back to where you've gone before. Once you've experienced the spiritual warfare of the sixth day of the Christmas Oratorio, it makes no sense to return to the unalloyed rejoicing of the first day- at least not for another twelve months!

But this cantata is different. Here, the form is far more architectural than didactic. Its five movements are carefully balanced as a Renaissance altarpiece; they don't contradict each other or seek to juxtapose emotions. Instead, they are much more homogenous. Indeed, in the score they run straight on from one another without a break- a complete contrast to the later cantatas, where a moment of silence allows the emotional effect of each movement to blossom in the listener. Here, the movements can be appreciated simultaneously and as a whole.

Balance, proportion, saintly adoration- and some hideous scary monsters.

What does this actually mean? Well, from the very beginning Bach chooses not to take the opportunities for vivid word-painting that he might have done later. When the text opens with “Aus der tiefe rufe ich, Herr, zu dir” – “Out of the deep I call to you, O Lord” – you might expect a sepulchrally deep bass entry, rising to an impassioned climax. That's what composers from Thomas Morley in the sixteenth century to John Rutter in the twentieth have done when setting these familiar words from Psalm 130. But here Bach is playing a different game: less emotionally heart-on-sleeve, more formally balanced; less rhetorically direct, more abstractly beautiful. The chorus enters in the middle of their register, not growling away in the depths; and as far as I can tell, the falling pattern of notes on the words Aus der Tiefe doesn't signify anything- it just is, in the same way as the opening of a Beethoven sonata or the West front of St Paul's Cathedral just is.

That's not to say that there's no word-painting at all. When each part comes to the words rufe ich – I call – the singers are given a long note to crescendo on. The call cuts through the texture like a fervent prayer. Similarly, the vowel in the word flehens – weeping – is extended over a falling pattern, almost like a sob. But there are no extremes of register, no ground-shaking bass lines. It's a cooler, more detached sound-world: one that reminds me of sixteenth-century Renaissance polyphony more than of Bach's immediate Baroque contemporaries.

And so we run from the opening chorus straight into a duet for bass and soprano. Bach gives the words of the psalm to the bass, but sets it against words from a sixteenth-century chorale sung by the soprano. Two musical genres are fused together- the archaic sounding hymn melody and the right-up-to-date freer arioso style. It's a trick we've often heard; but this must have been one of the very first times Bach, the master-smith, made an alloy of the old and the new like this. (And yet I can't help hearing in the repeated notes of the “modern” bass part an echo of the oldest musical style of all: plainchant psalm-tones. Maybe I've just been spending too much time with monks.).

And at the moment the soprano part reaches the word Holz- “Wood”, that is, the wood of the cross- at the highest point of their melody, the character of the bass line changes. It rises in its register as the soprano line starts to fall; and the words change. In the first part of this movement, the bass was singing words of fear: “So du willst, Herr, Sünde zurechnen, Herr, wer wird bestehen ?” - “If you, O Lord, were to count up sins, who could withstand it?”. After the intervention of the crucial Holz from the higher voices, this changes to words of comfort: “Denn bei dir ist die Vergebung, daß man dich fürchte.” - “for with you is forgiveness, that we may fear you”. This line gave me a jolt. It seems strange to describe this as reassuring- why would fear be a good thing? But we need to step back to a more princely age to get inside the meaning of this line. It's a different sort of fear from fear of punishment. Rather the author of the psalm, and Bach too, are talking about an established relationship. The psalmist fears God in the same way as a subject (either in Bronze Age Israel or eighteenth century Germany) might fear his prince: a recognition of allegiance to one's superiors which is far superior to a fear of arbitrary punishment- a sort of fear without fear, as it were.

And we've reached the very centre of this carefully balanced five-part structure. If the external movements were like the extended side panels of an altarpiece, and the duet movement we've just heard was a more intimate depiction of a few selected characters, here we reach the central panel. The third movement is a setting of just one line from the psalm: “Ich harre des Herrn, meine Seele harret, und ich hoffe auf sein Wort.”- “I wait for the Lord; my soul waits; and I hope in his word”. The word harre- wait- is gloriously extended in descending scales, while the word hoffe- hope- is repeated underneath it. Waiting is supported and revitalised by hoping- both in real life and in the music.

And the fourth movement is the precise parallel to the second; another duet between an old-fashioned chorale, this time in the alto, and a dancing aria for the tenor who sings the words of the psalm. Again, the two text sources elucidate each other; the tenor sings that his soul waits for the Lord, the alto gives us a picture of the troubled sinner “Den sein Gewissen naget”, “who is gnawed by his conscience”. Who are they? The alto tells us- two Old Testament kings, “David und Manasseh”. The former was a sinner because he couldn't keep his hands off someone else's wife and sent her husband into the front line of battle to keep him terminally busy, The latter was an apostate, and far worse in the eyes of the grumpy Old Testament prophets. But their importance isn't just that they were sinners- they both were forgiven.

Finally we reach the last panel. Just like the beginning, we're back in a more expansive sound-world, with all the singers declaiming “Israel! Israel! Hoffe auf den Herrn” (Israel! Hope in the Lord!) and a dancing middle section. But while the first panel was all about our action, sending prayers “upwards” as it were, this fifth section is about what we receive. The arc is completed; the repeated word that comes through here is Erlösung- redemption. The cantata closes with a stately final cadence. No wild joy with trumpets and drums; this is a sober, intense meditation. It may not have been written explicitly for Lent; but this homeless cantata finds an appropriate place here as the austere weeks before Easter roll on. And when someone asks what you're giving up for Lent, you can say “Rhetorical excess in eighteenth-century church cantatas”.