To look at something through a bamboo tube; figuratively used to describe having a narrow or limited perspective, often used as a polite way to refer to one's own opinions.

(literary) to have a shallow or superficial understanding of a vast subject; literally to measure the sea with a gourd, often used as a metaphor for a narrow perspective in the phrase 管窥蠡测 guǎn​kuī​lí​cè