I am invisible, yet I make things clear, I can be shallow or deep, bringing distant things near. In silence, I speak, and in stillness, I show, reflecting both light and the darkness below. Without me, you stumble, yet too much and you’re blind, always ahead, but often behind. What am I?& O! o% n- G; P2 S$ X, z(欢迎访问老王论坛:laowang.vip)