Our chief problem is lack of firsthand knowledge. You see, none of us have ever been there.

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

You can hear this line at 01:23:10.119 in the Blu-ray version of the movie.

Quote context

[...]

- Where was I picked up?

- Oh, about here.

- Well, as you know, the Japanese aim to open the Bangkok-Rangoon section by the middle of May. Naturally, we're gonna try and prevent them.

- It's too far for bombers to carry an adequate load so we shall have to go in and smash it up on the ground.

- How you gonna get there?

- Parachute drop and then march.

- With demolition equipment through that jungle?

- Yes.

- Our chief problem is lack of firsthand knowledge. You see, none of us have ever been there.

- Well, I don't want to discourage you, Major, but...

- It should be interesting. Colonel Green has given me the Kwai bridge. I'm going to take a team in and blow it up.

- Lucky you.

- Uh, are you sure you won't have a cup of tea?- No, thanks.

[...]