Explanation: Tube: bamboo; spy: watch from holes or cracks. Look through the holes in the bamboo tube days. Analogy or see things one-sided narrow horizons. Source: "Zhuangzi Qiu Shui": "is the direct use of Glimpse days, with a cone that way also, do not have small or Down?" Examples: Rare person, such as from ~ also. ★ "Records of Prince Liangxiao family"