When I'm in a cave, I often find myself wondering what drove these people to go so deep to brave dangerous and narrow passageways to leave their mark?
当我身处洞穴之中， 我总会不由自主地猜想 是什么吸引人们到如此深处？ 是什么让他们在如此危险且狭窄的通道里 留下记号？