Silence is golden, though not if you work in broadcasting. It's scientifically proven that dead air causes premature ageing among producers and presenters, which should have made Shhhhhhh, a documentary examining the nature of silence, a no-go zone.
In fact, the programme was a labour of love for its host Lucy Powell who was once set a koan (a riddle) by a Zen master in India asking her what the sound was before a bird sings. She couldn't answer it at the time – "the only thing I knew was that silence was a multiple and complicated thing" – so here she assembled a group of experts in film, art, music, poetry, science and philosophy to try and crack it.
It was quickly established that, even in the dead of night, there's no such thing as silence. In the countryside the animal kingdom conspires to disturb one's repose while, in the city, there's the round-the-clock hum of traffic. Even when all seems quiet, it isn't. Buildings vibrate, wind whispers, our bodies quietly crackle, creak and gurgle.
"There's always a noise floor,'" said the neuroscientist Jan Schnupp. "As long as we're alive there will be molecules bouncing about... and that will generate minuscule vibrations that our ears will pick up."
The percussionist Evelyn Glennie, who is profoundly deaf, told us how she saw the body as "a huge ear. My whole world is about vibration and it's about resonance... Whilst the body is beating, whilst we are breathing, whilst we are able to blink, there is no such thing as silence."
Powell looked at the pregnant pauses in music, theatre and film, and made superb use of archive footage from the likes of Samuel Beckett, Max Picard, Laurel & Hardy and Harold Pinter. There were fresh interviews too, among them with the theatre director Robert Wilson who was magnificently lofty, and from the conductor Edward Gardner, whose love of his profession seeped from the speakers.
Later came a heartbreaking dissection of silence as a mark of respect. There was, we discovered, a difference between the organised silence that marks a tragedy and silence born from sheer horror. Visiting Auschwitz, Jonathan Sacks described its quietness as "the auditory equivalent of a black hole. This is silence that swallows words and robs them of meaning... the silence of the unheard cry."
Powell's initial assertion that silence was "a multiple and complicated thing" was exactly right, but it was the slipperiness of its subject that made Shhhhhhh so terrific. I loved it for the depth and breadth of its discussion, for its unashamed profundity, and that it made me feel joyful, and then sad, and then joyful again. I loved it for making me really consider something to which I hadn't given much thought before.
A final note: if you missed this, you're in luck as the BBC have at last launched a new app that allows you to download the majority of its programmes on to a phone or tablet and keep them for 30 days. Brilliant.
Also, the independent production company Falling Tree has created an online archive allowing anyone to access its treasure trove of documentaries. To my knowledge, they've never made a bad programme, but to get yourself started I'd recommend The Lost Genius of Judee Sill, Short Cuts or the Reimagining the City series.