Well, no one can make anyone believe something if they don't want to believe it.

3 seconds sound clip from the Fiend Without a Face (1958) movie soundboard.

You can hear this line at 00:40:02.400 in the Blu-ray version of the movie.

Quote context

[...]

- For this reason, I've asked Major Cummings to this meeting. He's going to help us in any way he possibly can. That goes for his commanding officer, Colonel Butler, who is very concerned about what's happened.

- Cut out the soft soap, Melville. Let's get down to brass tacks.

- All I know is, before this air base came here, we were doing fine. Now you and these Air Force fellows tell us that it's not radiation at all. Well, maybe you're right at that. I don't know.

- But forgetting about the deaths, how do you explain the change in quality of the cows' milk, even the quantity? Let the major tell me about that.

- Go ahead, Major.

- Well, no one can make anyone believe something if they don't want to believe it.

- But it has been positively proven that there has been no radiation affecting anyone in Winthrop. Not even the cows.

- As for the milk, I don't know enough about farming, but I would assume...

- Griselle did. He knew his business.

- And so do I.

- It was the noise of the jets that did it, nothing more. It frightened the herd. But I can tell you that the herd is normal again. They've got used to it.

- Thank you.

[...]