The voice in your head is the voice that helps guide a player. It is written to in Postbag 16. The voice, while not heard in game, is known to be charming and educated, and speaks with a comforting accent. The voice is so eloquent such that some believe it to be a gift to mankind from the gods themselves. The voice often prevents players from performing actions that serve no purpose.
It is a joking reference to examine texts and other messages that appear in the chatbox, such as "Nothing interesting happens".