On ‘Ambient 4 (On Land)’ – the final edition in Eno's ambient series – his palate shifted from electro-mechanical and acoustic instruments towards “non-instruments” like pieces of chain, sticks and stones.

“One of the big freedoms of music had been that it didn't have to relate to anything – nobody listened to a piece of music and said, ‘What's that supposed to be, then?’, the way they would if they were looking at an abstract painting; music was accepted as abstract. I wanted to try and make music which attempted to be figurative, for example by using lots of real noises”, he recalled to Mojo.

In a pioneering early incarnation of what later became widely-known as remixing, Eno explained, “I included not only recordings of rooks, frogs and insects, but also the complete body of my own earlier work making ‘On Land’, which involved feeding unheard tape into the mix, constant feeding and remixing, subtracting and composting.”

Conventional instruments do occasionally feature however, including Jon Hassell's trumpet and Bill Laswell’s bass. The album also features contributions from Michael Brook and Daniel Lanois