With what purpose did the Italian cardinal, Giuseppe Mezzofanti, learn whole new language over night?

One of the most famous polyglots of mankind lived in 18-19 century, Giuseppe Mezzofanti could fluently speak in 39 languages, and almost the same amount of languages he could freely understand. He could speak so many languages even though he never left the territories of Italy. Once he learned the language over night, so he could take the confession of overseas criminal who was sentenced to death.


SOURCE: http://www.nkj.ru/archive/articles/4582/
IMAGE: en.wikipedia.org