相传，汉明帝在梦里见到一个金人，大臣告诉他那是佛。于是公元64年，明帝遣郎中蔡愔等出使天竺（印度）求其道。
It is said that in 64 , Mingdi sent his official Cai Yin to Central Asia to learn more about Buddhism after a vision of a golden figure appeared to him in a dream , who a minister told him was Buddha .
蔡愔