人非生而知之者，孰能无惑
rén fēi shēng ér zhī zhī zhě , shú néng wú huò
Knowledge is not innate to man, how can we overcome doubt?
We are not born with knowledge, how does one achieve maturity? (i.e. without guidance from a teacher - Tang dynasty essayist Han Yu 韓愈|韩愈[Han2 Yu4])