The singer's slavery to even the most common of human ailments is difficult for the outsider to appreciate, so much so that when a singer has to cancel on account of the rhinovirus or one of its allies, the affliction being suffered is almost always beefed up to something more impressive sounding. During the winter months, every day is spent anxiously reading the phlegmatic runes - steaming to ward off a viral threat, anxiously trying the voice out in the morning, trying to work out if that dry lack of suppleness is infective or due to over-enthusiastic central heating. Having an upper respiratory tract infection - and we singers feel every nook and cranny of the upper respiratory tract, from its top to its bottom, obsessively tracing the progress of the most subjective sensations of infection - is for a singer the equivalent of pulling a muscle or a tendon for an athlete.

It makes us, despite the extrovert image of the opera singer, a very inward-looking breed, literally, obsessed with the health of tiny pieces of mucous membrane (the vocal cords) in the cartilaginous larynx, and of its surrounding tissue, all of it inside, and accessible only by the larynyscope (invented by a singer). Obsessive too. I shall never forget my wife returning home one afternoon to find me hunched over the computer transfixed by what looked at first glance to be a rather unappetising pornographic website. In fact, battling my first bout of true laryngitis, the ultimate voice-killer, I was scanning endless close-ups of infected vocal tracts, trying to get a grip on my condition. So I was prepared for the singer's experience of the coughs and sore throats that go with the flu. It is the irrational feeling that, however many times you've been through it before, this is the end. What I had forgotten was the overwhelming viral depression, which makes you wonder if you could be bothered even if the wretched voice did come back.

It is difficult to see the melancholy fit, when it is actually upon one, as creative; it saps action. Look at Dürer's female figure of melancholy, dark-faced, slumped, surrounded by all the instruments of creativity but unable to use them. Yet from the 17th century on, melancholy and creative frenzy were seen as intimately connected, part of the cultural construction that became the still reigning notion of the artistic genius, Beethoven its prime exemplar, brooding and also, interestingly, dark- faced - a sufferer from the black bile, perhaps. Music retains a two-sided relationship to melancholia, both a curative, as David soothed Saul, and a quintessence, a sort of licensed wallowing. Or is it just playing at melancholy, perhaps, a steeling oneself for its unpredictable, material descent? The Jacobean Robert Burton is the anatomist of all this, from the music that "rears and revives the languishing soul", that which "makes melancholy persons mad...the sound of those jigs and hornpipes...not [to] be removed out of the ears for a week after", to the music which causes a "pleasing melancholy...[which] expels cares, alters...grieved minds, and easeth in an instant".