These range from the utterly banal (a housewife doing the ironing – actually the countertenor soloist in drag) to the specific (a couple of men taking technical measurements of one of the rooms) to the slightly bizarre (a man hanging crucifixes throughout the house and a masked, gloved figure who might just represent Death). Elsewhere in the house, a lady displays paintings on an easel, a party celebrates Christmas, a child bounces a ball and a coffin is carried out. What renders all these actions particularly peculiar is the way in which the protagonists carry them out, seemingly completely oblivious to anyone other than themselves or, sometimes, their little group.

This is Actus Tragicus, the work of the late Herbert Wernicke, as performed by members of the Stuttgart Opera Chorus and soloists. Wernicke was a maverick and prolific German opera director and designer who created productions of everything from Monteverdi’s Orfeo to Wagner’s Ring Cycle and 20th-century operas before his sudden death in 2002 at the age of 56. The starting point for this piece, which will be presented at this year’s Edinburgh International Festival, is six of the sacred cantatas Johann Sebastian Bach wrote for the Sunday services of the Thomaskirche in Leipzig. Here there is no central narrative, nor did Wernicke attempt to impose one when putting the music on the stage. Instead there are lots of tiny, seemingly inconsequential narratives. It is, in effect, a staged Bach performance that approaches the composer’s work from a completely different angle; nevertheless, in the EIF programme, it’s filed under the heading of opera.

Contemporary opera is a risky business. It’s extremely expensive to commission, and that’s without taking into account the costs involved in creating a brand-new production or the fact it’ll probably need more rehearsal time than a standard repertoire piece. Finally, given the reluctance of much of the general concert-going public to brave challenging, modern music, it might not even attract much of an audience.

Small wonder, then, that opera houses in recent decades have been increasingly drawn to the idea of creating new-old stage works. The idea is simple: take a classic musical piece usually performed in the concert hall and put it on the opera house stage – new opera without any of the risks of stepping into the unknown with contemporary music. This approach has been applied to everything from Schubert song cycles to 20th-century choral works, but it is with Handel and Bach that it has proved particularly successful. (Wernicke brought many concert hall works to the stage, including a number of Handel’s oratorios – he was working on a production of Israel in Egypt at the time of his death.)

Handel’s oratorios are extremely operatic, and it doesn’t take a vast leap of the imagination to envisage them on the stage. Bach presents more of a challenge, but his music is particularly irresistible to the opera director since, unlike Handel, he didn’t write any operas in the first place, and so the only way to get his music into the opera house is to stage one of his concert works. (The discussions as to why Bach didn’t write any operas roll on; some claim that such a godly composer wouldn’t sully himself with the secular nastiness of the opera house, but I’ve always found the argument that he never worked in a town with a court opera to be more persuasive.)

Bach would probably be rather surprised – perhaps even horrified – to discover that, 250 years after his death, people are intent on putting his Passion settings on the stage, but in recent years it has become rather fashionable. In the UK alone there has been a very successful production of the St John at English National Opera, which has been revived several times, while Glyndebourne staged the St Matthew a couple of years ago.

The Passions contain narrative – even if it’s a story without too many surprises – individual characters and dramatic action, all of which makes for a fairly straightforward translation to the stage. Not so the soundtrack that makes up Actus Tragicus. The texts of the chosen set of cantatas make for pretty gloomy reading, dealing as they do mainly in human frailty, the general futility of life and the inevitability of death. Against the angst of the texts and the suitably tortuous and crunchy harmonies to which they are set, the final cantata – the so-called Actus Tragicus from which the production takes its title – appears as a kind of catharsis. Which is not to say it’s particularly cheerful: it was written for a funeral.

“The problem today is that we try to forget about the presence of death in our daily lives,” says Albrecht Puhlmann, the general director of Stuttgart Opera, who is bringing Actus Tragicus to Edinburgh and who originally created it in Basle with Wernicke in 2000. “Bach’s music has a lot to say about eternity and questions of life and death; indeed it comes much closer to these issues than most operas.”

As to all the little actions being repeated over and over on the stage, Puhlmann says it can be seen as a reflection of life. “So much of what we do is in vain,

yet Bach gives these actions a sense of purpose – it’s as if these everyday actions become extraordinary through his music.”

Actus Tragicus is at Edinburgh Festival Theatre on September 4 and 5, 7.15pm, www.eif.co.uk, 0131 473 2000. These performances are supported by Dunard Fund. The Herald and Sunday Herald are media partners of the 2009 Edinburgh International Festival.