画龙点睛huà lóng diǎn jīng

以唐·张彦远《历代名画记》所述张繇僧画龙点睛的故事，比喻绘画、作文在紧要之处加上一笔，使其灵活而有神。

英add the touch that brings a work of art to life; add a word or two to clinch the point; put life into sth.like dotting the eyeball in painting a dragon;