- And if he is the person he believes himself to be, just as you are, then he's just as sane.
- Granted, but he isn't.

9 seconds sound clip from the Miracle on 34th Street (1947) movie soundboard.

You can hear this line at 01:10:04 in the Blu-ray version of the movie.

Quote context

[...]

- Not necessarily.

- You believe yourself to be Judge Harper, yet no one questions your sanity because you are Judge Harper.

- I know all about myself, young man.

- Mr. Kringle is the subject of this hearing.

- Yes, Your Honor.

- And if he is the person he believes himself to be, just as you are, then he's just as sane.

- Granted, but he isn't.

- Oh, but he is, Your Honor.

- Is what?

- I intend to prove that Mr. Kringle is Santa Claus.

- He's crazy too.

(Doorbell Buzzes)

- Hello.

- Hello, darling. Sorry I'm late.

[...]