It certainly helps to learn to be deliberate with language. Particularly in formal writing, and to a large extent in creative writing. This, I think, is the cen

It certainly helps to learn to be deliberate with language. Particularly in formal writing, and to a large extent in creative writing. This, I think, is the central problem in English instruction today. We try to teach arbitrary rules when what we need to teach is deliberateness. Learning other languages certainly helps the user understand their own language more (nouns, subjects, objects, adverbs, etc.) in a nuts and bolts kind of way, but it doesn't really help with writing (well) or comprehending the more advanced forms of the language. Fitzgerald, Hemingway, the writers of the King James Bible, Jefferson and Joyce are all vastly different from each other in their use of the language -- yet we hold all of them up as defining the flavor and character of the language in ways that are highly contrary to the thinking that produced S&W's Book and Lowth's Book. Most of English grammar instruction, and particularly guidebooks like S&W and Lowth seek to define and tackle imaginary English language edge cases that simply don't exist in other languages. "Don't split and infinitive" is not an edge case useful for consideration in Latin-rooted languages because you simply can't. It's also not an edge case in German because infinitives are always split (like in English). Other cases, like proscriptions to use "whom", fall flat because they are simply archaic or invented as a kind of shibboleth to demark persons with education from persons without. In modern usage, a person who uses "whom" is ultimately marking themselves as ignorant of the modern tongue. Learning a bit of Latin is hugely useful for understanding individual English words with Latin roots, and for fudging your way around Romance speaking Europe (it's astounding how much French an well educated monolingual English speaker can translate). But so is learning a bit of Greek useful in a similar way, and again German in other similar ways. Ultimately, the best way to learn about language is to study linguistics, not just another language. The very first thing you learn in linguistics is that there is none of this "correct" proscriptivist nonsense in a serious study of languages - at least not in the sense of the ignorant grade-school grammar guides we all grow up with. The most salient point to all of this is that the authors of those guides could not even keep in agreement with their own rules within the same guide!