You blow up a balloon, it floats. Same thing ought to work for bears.
7 seconds sound clip from The New Adventures of Winnie the Pooh - Where Oh Where Has My Piglet Gone? / Up, Up and Awry (S2E7).
You can hear this line at 00:16:02.327 in the Blu-ray version of the TV Series.
Quote context
[...]
- Just when we're least expecting it...
- Pooh really is trying to fly.
- I believe I would have stayed up that time, had I not come down.
- Why, the whole idea is hippoposterous! Isn't it? Of course, it is... I think.
- I know! We'll ask Owl! He'll know if Pooh bears were meant to fly.
- You blow up a balloon, it floats. Same thing ought to work for bears.
- Just don't forget to flap, Pooh.
- You mean Pooh would be a criminal?
- Oh, dear, we have to stop him.
- Given the nature of updrafts and downdrafts, and cold drafts...
- Oh, my.
[...]