I'm currently reading this charming book about Guarneri 'del Gesù', written in 1974 by Leonard Wibberley. I found it on a bookshelf and didn't realise it's actually supposed to be for children (imagine a children's book about lutherie – it had to be the 70s!).
So it's very readable, in a quaint sort of way, although it presents rather a dark view of the great maker. He's drawn as a violent drunk whose instruments sound good but who could never be bothered to finish them nicely and was always struggling to make ends meet, and was therefore known in the city as 'the worst violin maker in Cremona'.
He comes across rather the Salieri to Stradivari's Mozart, although sometimes the competition between them seems to be more metaphysical. A sample conversation (written from the point of view of Guarneri's apprentice):
'He looked at the instrument closely, shook his head, and said, "Signor, the voice is that of an emperor, the clothing that of a beggar."
"Signor Stradivari," replied my master, a little annoyed. "As God is concerned only with the soul and not with the body or its appearance, so I am concerned only with how my instruments sound and not how they look."
"Nonetheless," said the other, "if you took more pains, you could sell your violins to kings."
"Signor," said my master, "I do better than that. As you will see from the label, I give my violins to Christ – the King of Kings." And this was so, for, in every instrument he made, my master put the letters "I.H.S.," signifiying that they were dedicated to Jesus, the Saviour of Man.'
I've just got to the bit where Guarneri's gone on a bender, beaten someone up, landed in prison, and none of the other makers will bail him out because they don't have the money. It all kicked off with him visiting Stradivari and throwing one of his own violins at him saying, 'Haven't you made enough violins, old man? You say I drink too much? Well, you have a fault too. You make too many violins.'
Hmm. For the putative meeting of the two greatest violin makers ever, it's a little disappointing. But what do you think they might have discussed?