[retrac]

The boundaries between languages over time are as elusive as they can be between dialects in the present day. Most educated people can read English prose from the 1800s on a familiar topic and generally understand it. It's English. But to be fair, some will struggle. Further back in the 1600s, it's much harder. Does it need translation? If we go back to the 1400s, there's general agreement that it's Middle English, which is a different language, and it needs translation, as even many educated fluent speakers can't make heads or tails of it.

One of my textbooks in high school had a translation of Shakespeare into modern English, alongside the original text in both original and modernized spellings, with glossary and cultural notes. I'm not sure I'd have understood even it half as well without those.