鍵かぎの穴あなから天てんを覗のぞく

expression, godan verb (-ku)

have a narrow view of things; peep at the sky through a keyhole (lit.)

Idiomatic expression meaning to have a limited perspective or to judge things based on insufficient information. The literal image is of trying to see the vast sky through a tiny keyhole.

• 彼かれの意い見けんは鍵かぎの穴あなから天てんを覗のぞくようなものだ。

  His opinion is like peeping at the sky through a keyhole.