管窺蠡測（管窺蠡測）　

◎ 管窺蠡測 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] 管中視天,以瓢量海水,喻眼光狹小,見識不廣或不自量力

我昨兒晚上的話竟說錯了,怪不得老爺說我是“管窺蠡測”!——《紅樓夢》三十六回