The answer would be:
to inform the audience of the events leading up to this point
In Hamlet Horatio is a logical thinker and trusted by the people by making him giving this speech he tells the story to the people and people belive him, this way hamlet uses the trust people have in horatio so unveliebable events such as ghosts of dead kings talking to their children wont sound so crazy.
Answer:
sorry I didn't understand your question I am really sorry
