Zinka Milanov said that a performer must know his or her limits. 'If you are a cat, then you are a cat; no matter how much you may hanker to be a dog.'
We've all done it - for whatever reason gone up for things we can't manage.
I once took on a performance of Haydn's Creation when my voice was misfiring in the no-man's land between high baritone and high baritone with a cold. I certainly didn't have the low notes for By Heavy Beasts the Ground is Trod.
But If I didn't sing on the day before the performance, I told myself, my voice would be not so much sweet and low as cold and low and I might just get away with it.
We rehearsed all afternoon. By the time I went on my voice was hot.
I was bothered. And bribed two basses in the choir.
'When my part dips below this note,' I said, pointing at the score, 'put your copies in front of your faces, please, and join in. Beers on me after.'
The review in the local paper said that though I seemed at first to lack the heft required in my lower range, during the Heavy Beasts section my bottom notes sounded like the rumbling of approaching District Line trains.
But, still, I oughtn't.
And neither ought Silly Willy.
Remember from The Tinworth House Witch blog how to enter the Llangollen International Eisteddfod I pretended to be a Welsh speaker and the druid committee banished me from the field to help my aunty Sophia in the farmers' catering tent? Well, fast forward fifteen years and I'm back at the Eisteddfod. This time, preen preen, being chauffeur driven to and from my double bill at the Tobacco Factory in Bristol, performing a pair of Madame Galina sets on Family Day, for a fee of five months' rent.
I was in the green room warming up for my second set. A Ukrainian male folk dance troupe lined up in front of me to bow with their hands on their hearts. Then a semi-druidic steward hurtled up.
'You must come now, please, there's been an emergency just before you in the amphitheatre and people are leaving!'
Holding my tutu skirt against my belly in the approved manner I trotted back across the field with him. Families were scrambling up the sides of the amphitheatre. I went into character as Madame Galina and cajoled them into coming back. I was like an acidulous, frou-frou and Swarowski covered, pink-knickered sheep dog, apparently. Once I had them seated, I went into my routine.
At fouettes end I asked a St John's Ambulance volunteer what had happened before I went on.
'What did you say, love?' She was squat, with silver hair curling over the front of her hat. 'Sorry, I was day-dreaming standing here.'
Of one red-letter day having to use a defibrillator, of skull fractures protruding through scalps or an outbreak of the Black Death.
'What happened before I went on, why were they leaving?'
She pointed like the Sibyl at a performer standing sheepishly to one side. 'He did it!'
'Silly Willy?' I knew Silly Willy from the later-night, shall we say, cabaret circuit. 'He was in the Family Day venue, with the children?'
'The organisers assumed they'd booked a children's entertainer. Except they hadn't.'
'No, look how pale people still are.'
Silly Willy plays a children's entertainer. Who's alcoholic, has a potty mouth, and a fake penis hanging out of his trousers with a sign above it offering Free Sex Here for the Kiddies!
The St John's volunteer said, 'But really, how could the organisers not have known?'
I shook my head. 'The point is - Silly Willy himself would have known.'