You live a life for every language you speak.
I love this proverb.
It's simple, powerful and true, like all proverbs, but without a popular counterpart in English-speaking culture that would make it feel cliché and dead. We've all heard "birds of a feather" and lines like it way too many times for it to mean anything anymore. That's what's great about other languages' proverbs— they're all about the same stuff, but coming from such a totally different angle that you're capable of experiencing their elegance and profundity all over again, like a child.
Let's look at it literally. "Kolik jazyků znáš," word for word, is "how many tongues you know". (Interesting how 'tongue' is a synonym for "language" here as well!) "Tolikrát jsi člověkem" is trickier: "so many you are a human". So the proverb tells us not about lives, but about people. And this is so true. People tell me that they just feel different when thinking in another language, as if they have many selves—not fractured, but distributed, like colours.
And I like the ominous implication that a monoglot lives only once. Want to be immortal? Crack open those books and turn on Telemundo.
Moral of the story: languages are cool.
[Irrelevant PS: the first translation my dictionary offers for the word "člověkem" is "joker", not "human". Other translations are "subject", "soul" and "heart". I dig how these concepts are conflated into one word—especially "joker". It reminds me of "The Solitaire Mystery" by Jostein Gaarder, author of the great philosophy primer "Sophie's World", and of the neo-Jungian philosophy that Professor Jordan Peterson enjoys. For Gaarder, the philosopher is a joker, the misfit card not easily categorized, even ostracized, but with immense, subtle, metasystemic power. For Peterson, the joker is the Trickster, part of the great archetype of the Child or Selfhood. Either way, the joker is a metonym for human wisdom and human nature. Not that this is probably why the words are synonyms in Czech, but I think it's cool that they make sense together on this (extremely academic and arcane) level.]