Can One Ever Hope to Truly Learn Another Language?

My students aren't the only ones who are learning about language in my classroom. I am constantly aware of the idiosyncrasies of English, wondering why we do say "headache" but not "armache." Why "ph" sounds like "f" and why we "take a walk" (try explaining the logic of this verb choice!) and "go for a run." But I'm also learning about their language, and what I've always been told about how language influences thought is becoming quite clear to me. In Hmong, for example, their word for "woman" is the same word they have for "wife." During our classroom unit, they couldn't believe how many different words we have for what they simply call a "book." In their language, a folder is a book. A binder is a book. A notebook is a book. And I imagine, in a preliterate society, one word is probably sufficient. It's no wonder that my efforts to learn French have gone nowhere; I am acutely aware of how incredibly complex and culturally intertwined language is, and the task just seems impossible...