Jon Hassell (1937–2021) was a visionary composer and trumpeter whose seminal "Fourth World" sound unified ancient acoustic traditions with cutting-edge electronic processing. Over a pioneering career spanning five decades, collaborating alongside artists ranging from Brian Eno and David Byrne to Ry Cooder, Hassell radically redefined ambient music and trumpet performance. In his final years, he introduced his Pentimento concept: adopting a term used for a painterly techniqe to describe fragments of found sounds or performances that have been sampled, manipulated and recontextualised. Through this final trilogy, Hassell cemented his already well established status as one of modern music's most singular composers and inventors.

Music Is Invisible (Pentimento Volume Three) may now be seen as both a part of a sunblime final chapter in his creative journey to and a poignant final curtain on his performance career. Completing the trilogy alongside Listening to Pictures (2018) and Seeing Through Sound (2020), this posthumous release is constructed around recordings from Hassell’s final live concert appearances. Working with long-time collaborators Gregg Arreguin and Jeff Rona, Hassell applies his signature sound-painting process, coaxing live improvisations to morph into ghostly, overlapping dimensions. Across four expansive tracks—including the nocturnal blues of "Blue Ba-Ya", the stuttering, metallic pulse of "Club Gris-Gris", "Broadway Boogie-Woogie", and the haunting 16-minute epic "Electric Forest", his trademark harmonized trumpet floats through shifting, drum-less polyrhythms and shimmering textures. 

Music Is Invisible is a masterful farewell, offering a transcendent, eternal glimpse into the invisible realm of Hassell’s Fourth World.

The album covers of the Pentimento series mirror Hassell’s sonic philosophy. While Listening to Pictures and Seeing Through Sound relied on abstract, translucent layers (designed by artist Dan Keuhn) to mirror the pentimento effect, Volume Three introduces a vivid surrealism through Mati Klarwein’s 1976 painting, Leh C’est Beau.  The cover presents a detailed, otherworldly landscape where figurative nature and psychedelic symbolism converge. Followers might recognise that Klarwein's legendary artwork adorned Hassell’s seminal 1980 album Fourth World Vol. 1: Possible Musics (with Brian Eno) and the covers of many iconic albums for Miles Davis, Osibisa, Santana and others.