The last of this season’s Proms Choral Sundays featured one of the most complex of all choral works, Beethoven’s massive Missa Solemnis, written around the time of his 9th symphony. Sir Colin Davis likened performing it to “Failing to reach the top of Mount Everest”, and Sara Mohr-Pietsch (in her excellent Proms Plus talk) mentioned the description of “the most famous work you have never heard”. For many years I have been uncertain about this work. The complexity of his musical language does not make it an easy work to comprehend. It brims with uncertainty and confusion. Beethoven seems to be far more comfortable and assured when writing about the power and spirit of the human condition than about his perception of an (apparently) all-powerful God – this is no Fidelio or 9th Symphony. But I have not heard a more convincing interpretation than this one by Sir Colin Davies, an intrepid supporter of a work that seemed (more than ever in this performance) to be very close to his own heart. Although not without occasional performing hiccups, the combined choirs were very clearly on Sir Colin’s side, although some of the soloists seemed to be on a different planet, with Helena Juntunen, in particular, giving a far too operatic performance, vocally and physically. Sarah Connolly was the vocal star, along with flautists Gareth Davies and violinist Gordan Nikolitch. I also liked the contribution of Catherine Edwards on the Albert Hall organ.

As Sara Mohr-Pietsch pointed out, the work features strong contrasts of mood and volume and frequent examples of contrary motion. For every upward sweep of the music, there seemed to be a countering downward movement, perhaps indicative of Beethoven’s mixed feelings about the Godhead. The Kyrie is perhaps the most orthodox movement but already includes the ominous trumpets and timpani strokes that will feature so disturbingly at the end of the work. The Credo is one of the most dramatic moments of the whole work. It starts by contrasting loud and soft passages (already a common occurrence) before breaking into a short-lived fugue at Constubstantialem Patri and some vivid word painting at Descendit. Then starts one of a series of magical moments. As the tenors intone Et incarnates est and the soloists take up the strain, a solo flute flutters like a bird high above the voices, reflecting, it seems, the Holy Spirit “flying down to impregnate Mary”, as Sara Mohr-Pietsch so delightfully put it in her talk. The following Crucifixus is accompanied by jagged sforzando interjections until the choir sing, unison, Sub Pontio Pilato and the soloists take up the repeated refrain of Passus (this repetition of a key phrase will occur again) before the choir intone the dying phrase et sepultus est. In one of the great transitional passages of all music (alongside passages in Beethoven’s own 5th Symphony and Bach’s St John Passion), the tenors then burst in with (in this case, an almost shouted) Et resurrexit before the full choir enter with striding ascending passages. The brass add an air of judicial pomp to Judicare, the quick and the dead receiving similarly striking musical metaphors, as does the phrase Cujis regni (“whose Kingdom shall have no end”) in a passage of music that could, in theory, become endless. A return to the opening theme leads to another magical moment at Et vitam, the extended final phrase of the Credo. It starts with a breathless soto voce fugue (with some scarily high soprano notes), passes through a sinuous passage for solo voices (with more examples of contrary motion passages) with the flute again rising to the stars. Then a very curious loud staccato yell of A-MEN from the choir briefly shatters the mood before the movement dies away. What was Beethoven thinking when he wrote this?

In sharp contrast to Bach’s outburst of joy, Beethoven’s Sanctus is marked “with devotion” and sounds hesitant and uncertain, as if he was completely overawed and uncertain as to how to address the Almighty. He is far more confident when he comes the recognising that “Heaven and earth are full of thy glory”. Just before the Benedictus he inserts a memory of his childhood when an organ prelude would have been played at this moment, in this case substituted with a beautiful slowly evolving sequence for the low strings and flutes. The Benedictus is yet another magically mysterious moment with a soaring violin solo endlessly entwining the soloists.

The Agnus Dei is perhaps the most striking and curious of all the movements. The horns and bassoons cloud the bass intonation which, with the choir and other soloists, becomes increasingly uncertain about their plea for mercy and for peace. Then, just as the entire work seems to be settling into a conclusion of calm repose, marked in the score as a "Prayer for inward and outward peace", the immediacy and gravity of the plea for peace is emphasised by the unexpected arrival, in the form of trumpets and drums, of an approaching army. Although the music eventually dies away, apparently peacefully, the distant thud of the drums is still present, as is the ever-present contrary motion – which way will it go? Here speaks the Beethoven who lived through the carnage and misery of the Napoleonic wars. Whatever his views on the indomitability of the human spirit, as expressed in Fidelio and the 9th Symphony, his notion of God is less certain. There is no redeeming culmination, no comforting conclusion – the repeated pleas of Dona nobis pacem appear to have been in vain. In the end, the music just stops.