"What are you, then?" Buffy asked, tense and ready to strike.
"It's complicated." The strange man, about forty, with salt-and-pepper hair and green eyes, regarded her calmly as he replied, not appearing to be at all intimidated.
"Simplify." Buffy's voice was curt, her tone abrupt and demanding.
"A lot," Xander interjected.
The man sighed. "I'm the incarnation of the knowledge the universe has about itself."
A chorus of confused noises gave evidence of the Scoobies' lack of comprehension, and got them an eye-roll in return.
"I know everything that anything in the universe knows. I am that knowledge given form."
"You know everything?" Willow asked incredulously, simultaneously with Giles' "You're omniscient?"
"No, I know everything that anything in the universe knows. I don't know who'll win the next World Cup, but I know who's won an Oscar as soon as they count the votes - make a killing in Vegas. Especially when someone starts shaving points."
"Amazing," Giles breathed.
"Nah, happens a lot. Especially in college ball. Some of those kids'll screw their team in a heartbeat for a couple grand in cash."
"Oh! What if two people know something about the same something, but they each think a different something about the something? One of them has to be wrong, right? But they each know it, even though one of them is wrong about what they know, you know?"
"Then I know both somethings about the something."
"But how do you know which is right?"
"I don't, unless someone else knows which something is right. I just know what everyone knows."
As the three of them tried to build an understanding of the man's abilities, Xander and Buffy discussed the man's bona fides.
"Think he's for real?" Buffy asked Xander, more relaxed now, but still wary.
"Completely on the up-and-up. No doubt."
"Wow, you're Mr. Certainty. How come?"
"He understood Willow-babble."