This probably is my favourite bit from the book -

"People have stars, but they aren't the same...
.... You, though, you'll have stars like nobody else."

"What do you mean?"

"When you look up at the sky at night, since I'll be living on one of them, since I'll be laughing on one of them, for you, it'll be as if all the stars are laughing. You'll have stars that can laugh!"

And he laughed again.

"And when you're consoled (everyone is eventually consoled), you'll be glad you've known me.
You'll always be my friend. You'll feel like laughing with me.
And you'll open your windows sometimes just for the fun of it... And your friends will be amazed to see you laughing while you're looking up at the sky.
Then you'll tell them, 'Yes, it's the stars. They always make me laugh!"