Talk to the Speaker at the North Tower in the Tower.
"As we go I'll try to provide you with a little running commentary on how people have changed since you showed up. That's right: given to the Guardians by the Traveler so that I can read inter-departmental reports and mail. Just what it intended.
The Speaker. The old man's actually gotten a lot quieter since we showed up. He used to be a lot more talkative. To me, at least, he seems like he's spending a lot of time just thinking about something."
—Ghost