[HappyKasper]

It's often said [0] that every language is conducive to a unique worldview - in my personal experience, I see the world very differently in Polish than I do in English. Yet even if that worldview perspective may be intangible (i.e. hard to prove), the simple cultural value of each language is tremendous. Losing a language is like burning the Mona Lisa - along with every photo, copy, or file of her ever made.

[0]: https://mobile.nytimes.com/2014/12/07/opinion/sunday/why-sav...

[klodolph]

Your personal experiences are probably swamped by the fact that individuals have different personalities when speaking in different languages, due to the experiences that they've had speaking those languages. For example, it's not uncommon at all for an immigrant to have a very confident and assertive personality in their native language, compared to their personality when speaking the language of the country they live in. I know some people who are like this.

When I speak other languages I tend to be more serious. Perhaps this is because I was very serious when I was studying them? (Perhaps causation goes the other way?)