If the boy goes about saying the world is round, they'll take him for a lunatic.
4 seconds sound clip from the The Sword in the Stone (1963) movie soundboard.
You can hear this line at 00:53:57.843 in the Blu-ray version of the movie.
Quote context
[...]
- Well, what have I got to lose?
- That's the spirit. We'll start tomorrow. We'll show 'em, won't we, boy?
- Knowledge of man's fabulous discoveries in the centuries ahead.
- Now, that will be a great advantage.
- If the boy goes about saying the world is round, they'll take him for a lunatic.
- You mean, it'll be round someday?
- Man will discover this in centuries to come.
- And he will also find that the world is merely a tiny speck in the universe.
[...]