Claire Kramsch, a linguist at the University of California, Berkeley, tells him the question should not be "How many languages do you know?" but rather "In how many languages do you live?" Understanding the cultural nuances of a language requires extensive ongoing contact with its speakers, and for that reason Kramsch doubts that anyone could ever live in more than four or five languages.
Fair enough, but what about the less nuanced yet still astonishing feats of memory and computation that people display when they pick up a new language, or eight? Erard points out that, for no good reason, this question has been neglected by science. After all, we study extraordinary aptitude in mathematics and music; why not hyperpolyglots?
Erard tracks down Mezzofanti's papers, speaks to many fascinating language experts and even learns that some bilingual people experience mental illness in one language but not another. Most interestingly, he surveys a group of modern hyperpolyglots. Memory, motivation and practice are all important, they say, but so is pragmatism. Those who claimed to speak 11 languages did not much care about sounding like a native. Unlike Mezzofanti, their goal was not to dazzle but to do - see the world, read the local paper and not get lost.
D - kinda the basis for my idea of learning natural languages.
Just learn the parts that are regular.
For example, don't bother learning any Spanish irregular verbs.
Or English irregular plurals. Mooses. Gooses. Octopuses. Mitvots. And so on.
You'll be understood - and corrected. But so what.