None of us ever know the answer to that question until the moment arises.
4 seconds sound clip from the The Bridge on the River Kwai movie soundboard.
You can hear this line at 01:35:40.703 in the Blu-ray version of the movie.
Quote context
[...]
- I've tried to imagine myself. I suppose I find it hard to kid myself that killing isn't a crime.
- Well, I think that's all. Thank you, Joyce.
- Am I to go with the team, sir?
- Well, at least he was honest about it, sir.
- None of us ever know the answer to that question until the moment arises.
- What's your opinion, Shears?
- Well, sir, he's Canadian and that's in keeping with the international composition of this outfit.
- If he wants to go that bad, he can even take my place.
- Well, if you're all agreed on Joyce, he's yours.
[...]