In an interview with French magazine L'Express (long, but well worth a read), he reveals his enormous asset:
"When I conduct Mozart with the Vienna Philharmonic, the orchestra naturally provides the Germanic side of the work. For my part, I bring the Italian influence. The combination of the two, especially for the operas, produces interesting results, with a lot of character.
My knowledge of the Italian of Da Ponte's text is important. His librettos often have a double meaning. The first layer is suitable for polite society. And then there's another one, untranslatable and often....very daring. Mozart - who spoke excellent Italian - and his music often accompany the second meaning, not the first.
In Cosi fan tutte, when the two women recognise their lovers, they feel guilty. They say "Il mio fallo, tardi vedo." On the surface, this means "Too late I see my error". But the same phrase also means "I see the phallus" (of my lover)! In Italian, fallo has this dual meaning. It's not the same any more, is it? This kind of double sense is found a lot, often concealing erotic words."