As an actor, you don't want to know the beginning and end to...

As an actor, you don't want to know the beginning and end to your character's arc. It makes it more fun. You're not playing the end. You're playing it realistically. You don't know where this character is going to go and what's going to happen to him, which just makes it more interesting for the viewers to watch. They're going on the journey with you, as the actor and the character.