From 《
礼记·
学记》(Li Ji, Record of Learning, ca. 2nd c. BCE):
独学而无友,
则孤陋而寡闻 (If one studies alone without companions, then one becomes narrow and ill-informed). The four-character
孤陋寡闻 has since crystallized as a standalone idiom meaning 'narrow-minded and ignorant,' often used self-deprecatingly:
我孤陋寡闻,
请教一下 ('being ill-informed, may I ask...'). This entry preserves the full consequence clause with its
则 (then).