I think Nuncle's comment on editing being a casualty of our times is a comment on the regrettable fact that copy-editors seem to be among the first to go at newspapers and magazines when they decide they need to cut staff. This is often ridiculed with the glib phrase, "We don't need no copy editor, we got spell check." Of course, copy-editors do much, much more than correct misspellings. As for learning grammar in a modern European language from Latin, I don't know how it is in Nederlands but Latin grammar is a mighty poor match with English grammar. As has been pointed out we all learn the grammar of our mother tongues as small children, well before we are ready for any sort of formal training. This learning of the grammar is internalized and, while well established as an understanding of how to talk grammatically, does not give us any ability to talk rationally about it other than saying that an ungrammatical statement just doesn't sound right. For many of us the formal training either never happens or is so miserably inadequate in representing the true grammar of the language that it might as well never have happened. Learning any other language, one with a grammar sufficiently different from the grammar of one's own, at least gives us some notion about how grammars work. Any sufficiently intelligent person can then compare how this formally learned grammar works compared with the internalized grammar of their native tongue. This would work with any additional language learned formally. Languages learned in the same way as one's native language, by just being immersed in the language and forced to communicate in it, would probably not help with this. Multilingual people often learn other modern languages without formal training so it's usually Latin that gets the credit.
