Ella: Catherine's Daddy is very tall.
Me: Someday you'll be very tall.
Ella: Will I keep growing forever?
Ella (panicked): Why not?
Me: Because then you wouldn't fit in the car and we'd have to get a special bed made, but don't worry, your bones know when to stop growing.
Me: There's a space in between your bones that says, "Grow! Grow", and when you get older, it closes up and tells your bones to stop growing.
Ella: Is that space where God lives?
Sister: Exactly right, Ella.