A fall into the pit, a gain in your wit.

吃一堑，长一智。

《新英汉大辞典》

No, really. I guess it didn't fall out of the car after all. Look! My peach pit is inside it, too.

没开玩笑，是真的。我猜想它还是没掉到车外面去，瞧！我的桃核也在里面呢。

youdao

What I found is that unless I am on top of my game and choosing to "be productive", I easily fall back into the pit of procrastination, where time is never "of the essence".

我发现，除非我为了选择“更有效率”而非玩游戏，不然我又会落入拖延的陷阱，在这点上时间从不是“本质原因”。

youdao

"The Fall of the House of Usher" and "The Pit and the Pendulum."

VOA: special.2009.02.02

We know that those with so-called disabilities don't fall into the pity tar-pit and in fact, do better than they or anyone around them ever thought possible.

CNN: Amputees never say 'I can't'

Miner Ian Cameron, 46, died when equipment fell on him at the pit in October 2009 and Don Cook was killed in a rock fall in September 2008.

BBC: Pit death inquest: Gerry Gibson died from asphyxiation