Prom 47: BBCSSO, Exaudi, Volkov/ Prom 48: Coote, LPO, Jurowski, Royal Albert Hall

Radio 3 is embarking on a centenary talk-fest about John Cage, but there’s nothing to say about him that has not been said a thousand times already.

As his frustrated tutor Arnold Schoenberg observed, he was not a composer but an inventor, or as we would say a conceptual artist: replacing willed composition with games of chance, opening the door to the variegated beauties of silence, and putting the most humdrum household noises under a musically-revealing microscope, he led where armies of other artists have since followed.

But we still need to feel the truth of his message, as Prom 47 - curated (and conducted when appropriate) by Ilan Volkov - demonstrated in three fascinating hours. With the BBC Scottish Symphony Orchestra divided into three groups plus four ‘prepared’ pianos, the opening piece "101" sounded almost old-fashioned with its fastidiously organised layers, but it made us listen with new attention to the sound of applause, and to the sound of the orchestra routinely tuning up for their next piece.

"Conceptual" Cage - and the work of followers like Christian Marclay who had the orchestra rubbing, scratching, and bashing their instrument-cases – really doesn’t need to be heard at all, but the West Coast master’s vintage works which were performed here lit up the mind. In "Improvisation III" the players were simply armed with cassette recordings, the Exaudi singers limited themselves to one note each, and Joan La Barbara intoned an e.e.cummings sonnet with repetitions, echoes, and pregnantly interposed silences.

The simultaneous performance of three pieces at once worked sweetly, as did the free-wheeling, high-flying improvised "Quartet" and "But what about the noise of crumpling paper?", with Cage’s signature-work "‘Branches" - for stroked cacti and shaken dry grasses, all heavily amplified - casting its usual ecological spell; the imported soloists, many of them Cage-veterans, worked wonders with stone-age electronics. But still no answer to the central Cagean mystery: why should pieces which ought to sound irritatingly random have such delicate poise?

In Prom 48 mezzo Alice Coote transfixed her audience with Mahler’s "Lieder eines fahrenden Gesellen". The text is short and wistful, but Coote gave it the most wonderful resonance, with a sound of sustained richness and a coloration subtly graded along the gamut of pitch and emotion. Vladimir Jurowski and the London Philharmonic were her sensitive companions.