"Learn Esperanto to talk to the world."
Translation:Lernu Esperanton por paroli kun la mondo.
...paroli KUN la mondo? to talk with the world?
I would think that "al la mondo" would be better.
This is a sticky one, because what is "the world" and how would you actually talk to it? So the reference is to the inhabitants of the world.
This kind of fits into is this an English idiom that should be translated into non-idiomatic language before it's translated? Perhaps.
Fortunately, Esperanto can be as precise or as imprecise, as other languages are, and "paroli kun la mondo" is common usage.
So this one depends on the degree of precision you're looking for.
This is actually where I've struggled. I've had someone tell me that they thought it was idiotic to say "catch (or take) a bus to the city" in Esperanto, but others accept it perfectly fine. I guess it depends who you are speaking with and how accepting they are to figurative speech. Your thoughts?
EDIT: They preferred to say "I am going to the city by bus" which is fine to me, but I personally wouldn't use that phrase.