Title pretty much says it all. Which languages would be most useful to a time traveler?
closed as primarily opinion-based by Measure of despare., AlexP, Shadowzee, L.Dutch♦ Jun 27 at 4:47
Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.
My gut says Latin, and I'm not really inclined to disagree. Unfortunately, there are a lot of types of Latin, so if you have to pick one, choose Vulgar Latin. Latin's pretty useful, considering that half of Europe is derived from it, and every Western scholar, up until even half a century ago, was required to have a passing knowledge of it.
Chinese seems to be the obvious choice, but the problem is there are too many dialects. The most common is Mandarin. China never spoke one unified language (until recently, anyway) and I don't know the base tongue of it, and even if you did learn that, it's fallen to obscurity. English only real came into prominence with the rise of England and America, so that's out.