I received the following question:

In Acts 21:21 when Paul addressed the mob in Hebrew, I thought He was speaking in a Hebrew dialect we call Aramaic, which the Lord spoke to the crowds. Ancient Hebrew which the fathers spoke was long forgotten. But correct me if I am wrong.

I would tend to think that Paul was speaking Aramaic, not Hebrew, when he spoke to the crowd in Acts 21:21. Paul probably could have spoken Hebrew, but very few in the crowd would have known what he was saying, so their angry response to his comment about being sent to the Gentiles would be unlikely. It seems much more fitting to say that he was speaking in Aramaic. That, they all would have understood. The Bible probably calls it “Hebrew” since it WAS the language of the Hebrews at this time, actual Hebrew having died out and been forgotten.