I once took an undergraduate Poetry class and devoted my final portfolio to the translation dilemma that Thoreau touches upon here.
Essentially, I explored the dynamics of language and the ways in which translation often detracts from the native tongue. A beautiful, artfully crafted poetry verse in French, when translated into English, often loses its splendor and linguistic beauty.
Even the most fluent translators have no power to preserve the quality and true meaning of the native tongue.
Each language is its own entity, and simply choosing the words with equivalent meanings in another language does not do the original writing justice.
Translation occurs not only between languages, but also between dialects, language styles, and sub-languages. Thoreau describes language from a different time — even if it is the same “mother tongue”. The same principles apply; our mere 'translation' into modern-day English is insufficient.
It simply doesn’t compare to the true native language, or dialect, of writing.
William, this is a very thoughtful piece. I enjoyed reading it. I enjoy Thoreau, as well as Ralph Waldo Emerson. If you haven’t already, I would strongly recommend reading Emerson’s work. Good luck, and I will keep an eye out for your work!