translation.en: The human hand, in manipulation of objects, is the hand in search of a brain; the brain is in search of a hand; and play is the medium by which those two are linked in the best way.
translation.zh: 人类的手，是可以操控物体的， 是一双寻找大脑的手。 大脑同时也在寻找手， 而玩耍是最能结合两者的媒体。