gild the lily

Gild the lily字面意思是“给百合花镀金”。这种表达方式来自戏剧大师莎士比亚。他在历史剧《约翰王》中写道：

To gild refined gold, to paint the lily, to throw a perfume on the violet, to smooth the ice, or add another hue unto the rainbow……is wasteful and ridiculous excess.

给金子镀上金箔，给百合涂上颜色，给紫罗兰洒香水，把冰磨光滑，给彩虹添颜色，是多此一举的。

后来，paint the lily就演变成了gild the lily。

to improve or decorate something that is already perfect and therefore spoil it

画蛇添足，多此一举

例：

Should I add a scarf to this jacket or would it be gilding the lily?

穿上这件外套我再配条围巾好吗?不会显得画蛇添足吧?