I didn't know this song by Barbara; she was among the few at the time who wrote, sang, and played her own pieces.
The beautiful thing is that I discovered it through a cover by Anne Sofie von Otter and Brad Mehldau. Different genres and styles meeting. Even more surprising to find Michel Portal here - who at the time was also recording with Karlheinz Stockhausen: his saxophone dialogue with the singer is truly... interesting.