涨知识：13个让你看不懂的英文习语的起源

If you're "separating the wheat from the chaff," you're distinguishing between quality and worthlessness. The phrase actually comes from the Bible.
如果你在“把糠从小麦里筛出来”（separating the wheat from the chaff），那么你就在甄别精华和糟粕。这个习语其实来源于《圣经》。

Chaff is the protective casings of the seeds of cereal grain. Humans can't eat it, but livestock can. It's not as important as, say, wheat.
糠是保护谷物种子的外壳，人不能吃，但牲畜可以。它只是没有小麦等谷物那么重要而已。

In Matthew 3:12, John the Baptist says, "His winnowing fork is in his hand, and he will clear his threshing floor, gathering his wheat into the barn and burning up the chaff with unquenchable fire."
在《马太福音》第三章第12节中，施洗约翰说道：“他手里拿着簸箕，要扬净麦场，把麦子收进仓里，却用不灭的火将糠秕烧尽。”

In the Old Testament the image of winnowing is also used in Psalm 1:4 :"…the wicked! They are like chaff that the wind blows away."
扬谷的画面也出现在《旧约》里《诗篇》的第一章第四节：“…恶人！他们就像糠秕被风吹散。”