[thaumasiotes]

There is as much separation between the language of Alexandre Dumas and the language of William the Conqueror as there is between the language of William the Conqueror and the language of Theodosius, Emperor of Rome.

But you'd like to say that William the Conqueror was speaking French and not speaking Latin. Why?

[908B64B197]

The real question is: Given a text by William the Conqueror and Theodosius, how many words could a French or English speaker identify based on similarities with words he/she commonly uses?

[thaumasiotes]

That probably isn't the question you wanted to ask. But in case it is, you can see a book compiled by order of William the Conqueror here: https://opendomesday.org/book/bedfordshire/01/

High-resolution image of the same page: https://opendomesday.org/media/images/bdf/01.png