Bergman wrote in all genres but over half his output is choral. This collection might be subtitled ‘1936-2000’ but it maps the composer’s unaccompanied choral output in full. What we are really hearing is the central transition of 20th-century music charted via one man’s work. Bergman moved from a frustrated and short-lived post-romantic period through to Schoenbergian dodecaphony and eventually out-and-out serialism. In the latter, he clearly found his voice. Trusting only in technique, he delivered vivid, embracing, watertight and honest serial works that are as cleansing as they are challenging.

To witness that process portrayed musically is remarkable. In a work like Mitt träd är pinjen (1944) Bergman does a great deal with the material but the feeling is of pastoral reflection and the harmonies bear that out. In works from the 1950s such as Lamento – Burletta (1957, not an insignificant year for Finnish music) we start to hear the harmonic strain. By the time of the folk-song collection Tyttöset, Bergman’s tonality is creaking, splintering and faltering altogether, just as it does midway through Schoenberg’s Gurrelieder. These three folk songs are also the only works here to set Finnish; the resulting shift in the gait and syntax of Bergman’s music (next to the Swedish/Norwegian/German works) speaks volumes about language and its shaping of musical expression.

Eventually we get to Bergman’s late setting of the Kalevala’s runo 41, Väinämöinen (2000), which furthers his favoured structure of using a narrator (sung or spoken) in front of an echoing or scene-setting chorus. Bergman always knew what he was doing but here he appears to know himself thoroughly; the tools he finds to reflect the painful narrative – not least the parallel harmonies – have big impact. Performances from the Helsinki Chamber Choir are technically impressive. At best they ring out with Bergman’s conviction and talent; below that, they speak of a composer for whom technical matters came first rendered by a salaried radio choir on a Tuesday morning in October (this was formerly the Finnish Radio Chamber Choir). In that sense, they reflect their subject rather well.