Who's Smarter Now?

I was trying to reason with Adam that he still needs his nap during the day as he's never really liked sleeping.

"You need to sleep because that's when your brain grows. Do you know what the brain is?"

Adam (3yrs and 9months) says: "Yes, it's inside my head."

Impressed, I asked: "What is it for?"

Silence.

I explained: "It's what makes you smart."

Adam: "But I'm smart already."

He is.