"Let's talk like buddies", says my 9-year-old son as I tuck him in. "Who was the greatest person of the 19th century?"

Must be all that Wikipedia he reads before school. Hm. OK. Let's discuss it like buddies.

What does the greatest mean to you? The most influential?

"Yeah", he says. "The most influential. That'll work."

I venture a few trial guesses. Napoleon? Lincoln?

"I don't think Napoleon was influential", says my son flatly.

Why not? I mean, Napoleon, everybody knows Napoleon. I mean, empire, wars, battles, all that Napoleonic stuff.

"Nope." My kid is not impressed. "Because, look: what changed? What did Napoleon change compared to when he started to rule? Same countries, no change."

What about Lincoln? Winning the Civil War, ending slavery, uniting the country? How does that rank?

 "Nope", says junior. "In Europe, there was no slavery in the 19th century to begin with. So he just made us catch up to what's normal. By the way, Alexander II freed the serfs in Russia at the same time, and they didn't need a war for that."

Well, I'm stumped. If Lincoln's just a local hero, who is the greatest then?

"I don't know. Bismarck, maybe? He united Germany. Before him, there was no Germany, only principalities. What do you think?"

Bismarck? I think of that famous picture in a spearhead helmet. Then I wonder if the united Germany was such a good idea given what happened later on. On the other hand, maybe it's not Bismarck's fault. I feel a certain gloom. Maybe I'm just not rooting for Bismarck.

Oh, wait! What about scientists? Or philosophers?

"Like who?", my son asks.

Maxwell? Darwin? Marx? Hegel?

"Marx was only really influential in the 20th century", he says confidently. "So not Marx."

He doesn't know about Maxwell or Hegel yet. For some reason, that makes me feel better. I'd love to explain what they did, I say, but it's too late now. Maybe another day.

"Darwin? Some people say evolution is just a theory."

Well, every theory is just a theory, I explain. What makes it good is how often and how well it is confirmed by experiment. By that standard, Darwin's theory is excellent and most probably true, too.

"Well, OK", he says. "Maybe Darwin, then. Or Bismarck."

And with that, he turns on his side. "Good night, dad", he says.

Good night, buddy.

I gotta read some Wikipedia.