- Think about this. Are you quite sure you'd be able to use it in cold blood?
- I know how to use it, sir.
- That's not what I meant. Could you use it in cold blood? Could you kill without hesitation?

— (André Morell)

14 seconds sound clip from the The Bridge on the River Kwai movie soundboard.

You can hear this line at 01:34:42.645 in the Blu-ray version of the movie.

Quote context

[...]

- How did you happen to wind up here?

- In '39 I came over to London to enlist and about two years later I volunteered for this work.

- You volunteered?

- Yes, sir. You see, the regular army...

- Go ahead, you can be frank.

- Well, sir, the regular army sort of reminded me of my job in civilian life. They don't expect you to think.

- Think about this. Are you quite sure you'd be able to use it in cold blood?

- I know how to use it, sir.

- That's not what I meant. Could you use it in cold blood? Could you kill without hesitation?

- That's a question I've often asked myself, sir. It's worried me quite a bit.

- What was the answer?

- I don't honestly know, sir.

- I've tried to imagine myself. I suppose I find it hard to kid myself that killing isn't a crime.

- It's an old army problem.

- Well, I think that's all. Thank you, Joyce.

[...]