A misremembering

Watched most of Lawrence of Arabia again today, which has one of my favorite pieces of dialogue from any film. It goes like this:

"We can't just do nothing!"
"Why not? It's usually best."

The curious thing is that I had remembered that second bit as a line said by Alec Guiness's character. He plays an Arab king, so I took it as a little bit of Arabic wisdom, although I don't suppose the screenplay was written by an Arab.

However, I misremembered this. It isn't Guiness who says it. Rather it's said by a British General, who suggests doing nothing in response to a statement by one of his lower officers.

The different speaker gives phrase a different sense, I think. The British are hardly doing nothing in 'Arabia'
during the time period of the film. Yet in the instance in question, which is whether they should do something to help Lawrence out in his dealings with the Arabs, the General is for not helping - that is, doing nothing.