In The Sky I Am Walking, Greengrassi Gallery

Howard Blake fans, look away now. Am Himmel wandere Ich isn’t a back translation of the hit song from The Snowman. Though the Marxist-Adornist supporters of the party line at Darmstadt’s summer course of 1971 could hardly have thought less of Stockhausen’s song cycle when they heard it and then circulated a dismissive pamphlet. ‘Saint Stockhausen’, they called him.

The culture wars have moved on and found other targets. With the benefit of hindsight it seems obvious that Stockhausen was true to the rallying call he made at the time: “In every work there must be something that makes it utterly different!” The composers who lived up to this mantra are vanishingly small in number. Bach and Stravinsky must be first among them, who made each masterpiece singular, personal but different to everything that went before it. Stockhausen too. For many listeners he still defines the sound of “modern” music, for good or ill, in, say, the multi-orchestral clamour of Gruppen. To them, to anyone, In The Sky should come as a shock, and a delightful one.

In 12 songs drawn from an anthology of American-Indian texts, Stockhausen created a handbook for composers, but also audiences. The first text is sung to a single note, the second two, and so on, until all 12 notes of the chromatic scale are heard (briefly) in the "Song of a Man who received a Vision", giving the two singers their cue to leave the performing space, as they take the last four notes of the sequence (tone-row, or formula, as Stockhausen called it) with them. The idea is simple, and the execution was swift – he wrote it in a matter of weeks – but recordings can only hint at the richness of a live experience, such as was given in a spacious south London gallery by the tenor George Chambers (pictured above right) and soprano Rebecca Hardwick.

Having gained experience through both coaching given by the work’s first performers, and the previous dates of a UK tour, Chambers and Hardwick maintained a mesmerising pitch of intensity through the cycle’s 45 minutes as they sat before us and opposite each other, not only to sing but to perform the score’s notated actions – sprinkling water, strewing petals, sleeping and dancing – that make it a forerunner to the composer’s operas and communicate on several levels, none crossing the other but each running parallel like the lines of a pylon, conveying a strong, electrically charged consciousness.

In The Sky creates an entirely fresh ritual for itself

First, a humble respect for the texts – not only their realisation of Stockhausen’s notations but the powerful simplicity of the original poems, which move through universal states of love, war, grief and joy without being patronised or embellished in the settings. Yet, second, the performance nonetheless breathed the air of a German Lieder-cycle in the classic tradition to which Stockhausen belonged with various degrees of willing complicity during his career: the remembrance of a distant lover in the fourth song was straight out of Schumann’s Frauenliebe und Leben, as Hardwick intoned the refrain and Chambers traced her shape to one side. This is impressive less on its own terms than for the economy of means: four notes, seven lines, a few gestures.

Third, and this was what perhaps had angered the Darmstadt epigones most but should bring the work to a more receptive audience in our own time, it creates an entirely fresh ritual for itself. “Sacred I have been made” is the cry of the final song, with more than a touch of Goethe’s Eternal Feminine about it, and yet in Hardwick’s wide-eyed joy and assured dramatic soprano the line took on celebratory overtones of rebirth and renewal.

The pitch was unfaltering, the unisons uncanny, in Stockhausen’s cycle and the two brief works preceding it. Black Eyes by Daniel-Lewis Fardon is a mini-drama of alien abduction, less wacky than unnerving. The material of an excerpt from Cornelius Cardew’s The Great Learning was stretched too thinly for all its aspirations towards Confucian profundity. The evening belonged to Stockhausen, and to Chambers and Hardwick.