This Dacapo disc from 2009 collects some of Per Norgard's shorter piano works performed by Erik Kaltoft, and a diverse collection it is indeed. We find works from a span of 40 years, ranging from serious explorations of form to lighthearted tributes.
For this longtime Norgard fan, the main attraction was three works of the late Fifties in which the composer gradually uncovered the infinity series, his unique method of generating endlessly self-similar (fractal) lines. The Nine Studes op. 25b (1959) see Norgard working with a tone row whose successive statements are gradually altered rhythmically -- the composer compares his technique to the color and talea of Renaissance polyphony. There have been serialist composers who evoke the Romantic era, such as Berg and Rautavaara, but here we have 12-tone writing with the clarity of Baroque or early music. The work is not all simpleminded process, for in several of the studies the treatment of a tone row is only a second line heard below more freely composed music, but Norgard's dominant line features only tones that could be harmonically related to the peripheral one -- Norgard's characteristic interest in "interference" and deriving everything from one genetic code! The Four Sketches op. 24a (1959) are based on the same techniques, but lighter in mood and less complex.
Although Norgard had performed these experiments with tone rows that anticipated the infinity series, that remarkable musical phenomenon was first unveiled in Fragment I-VII, a series of works for varying forces. The first four, composed from 1959-1961, are for piano solo. These continue the pointillism of the Studies, but are more reserved and aphoristic, approaching Webern. ("Fragment V" for violin and piano can be heard on another Dacapo disc. "Fragment VI" for orchestra was infamously withdrawn after a single performance, when the composer realized that his complex structure couldn't actually be discerned by the ear. "Nocturnes (Fragment VII)" remains in his catalogue, but I'm not aware of any CD recording.)
The remaining music is less intense. "Cob Weaver and Other Secrets on the Way" (2002) is a diptych where the first piece consists of an accelerating line through the infinity series, while the second is more meandering.
Three pieces are heard here that form the collection Animals in Concert. In "A Tortoise Tango" (1984) and "Hermit Crab Tango" (1997) that dance form's rigid four-part time is combined with melodies that develop more freely. "Light of a Night -- Paul meets bird" (1989) is one of Norgard's tributes to the Beatles, where the melody of their tune "Blackbird" from the White Album is gradually fused with the sample of blackbird song heard at the end.
"Nine Friends" (1984), a series of coded messages to friends of the composer, is essentially a collection of bagatelles. There is some structural unity in that most of the pieces are variations of the same melody and the collection becomes progressively more virtuosic.