For Albert Schweitzer the Orgelbüchlein was ‘The Bible of Bach’. For Russell Stinson it is ‘simultaneously a compositional treatise, a collection of liturgical organ music, an organ method and a theological statement. These four identities are so closely intertwined that it is hard to know where one leaves off and another begins.’

Bach planned to make a compendium of 164 settings of chorale melodies, to cover the whole of the church year. He managed to complete just 45 of them, leaving most of the book empty, save for the chorale titles. In addition, there is a tantalising bar and a half’s opening of O Traurigkeit, o Herzeleid to set the player on their way.

One approach to filling in the gaps has been to commission contemporary composers to write their own chorale preludes, for example in the Royal College of Organists’ Orgelbüchlein Project of 2022. A more historically valid attempt to produce an expanded Orgelbüchlein is the subject of this handsome Fugue State Films project. Renowned as an improviser in Baroque idioms, the Dutch organist Sietze de Vries guides the viewer (and listener) through the background processes towards his completion of a further 45 of these ‘ghost’ chorales. He identifies the six main categories of chorale treatments, ranging from relatively straightforward melodic adornments, through elaborate canonic techniques, to fast-running ostinato accompaniments, in short – running the full gamut of Bach’s compositional genius.

De Vries is greatly helped by Bach’s existing chorale harmonisations from other sources and the fact that each prelude is quite compact. Spread over seven half-hour films (on one DVD and two CDs), two ideal ‘Bach organs’ in the north-east of the Netherlands are featured. The larger one is in the Martinikerk, Groningen, a substantial three-manual, notable for the only surviving 32ft Arp Schnitger Praestant rank, dating from around 1692. Its immense gravitas is used sparingly but tellingly. The Rugpositief is the largest department and de Vries fully exploits its poetic colours. The Sexquialter mixture has a beautifully tingling quality.

Delicate stops also abound on the two-manual organ in the Petruskerk in Leens, in particular the Speelfluit, which is so effectively gentle in the melancholic Lenten preludes. Both instruments provide thrilling plenum registrations in the more festive preludes.

What of these ‘new’ preludes? Is de Vries’s ersatz Bach convincing? The answer is a decisive ‘yes’. He is in total control of the idiom. His An Wasserflüssen Babylon flows smoothly and Aus tiefer Not schrei ich zu dir is especially haunting. He concludes with Bach’s own Liebster Jesu, wir sind hier, BWV634, with the melody in canon at the fifth, and deliciously daring crunches showing how it should be done.

Congratulations on such a stimulating enterprise. I wonder how many other players will be brave enough or inspired to tackle such a task.