An excellent example of the constant fluidity of language comes from Shakespeare. The Bard has Juliet say, "Romeo, Romeo, wherefore art thou Romeo?"

Speakers of modern English unfamiliar with the text uniformly believe Juliet is asking where her beloved is. But she isn't. She's asking why he had to born into the wrong family.

Wherefore means why, not where. But because our language has evolved, most of us don't know that. Reading the original text, we mistake the meaning. That's just one trivial example, but to put it into perspective, the distance in time between Shakespeare's English and our English is minuscule compared to the span Biblical texts have existed.