管窥蠡测（管窺蠡測）　

◎ 管窥蠡测 guǎnkuī-lícè

[take a narrow view of sth;look at the sky through a bamboo tube and measure the sea with a calabash——restricted in vision and shallow in understanding] 管中视天,以瓢量海水,喻眼光狭小,见识不广或不自量力

我昨儿晚上的话竟说错了,怪不得老爷说我是“管窥蠡测”!——《红楼梦》三十六回