" the eye were no more than sense organs. The brain was no more than a central switchboard, encased in bone and removed from the working surface of the body. It was the hands that were the working surface, the hands that felt and manipulated the universe. Human beings thought with their hands. It was their hands that were the answer of curiosity, that felt and pinched and turned and lifted and hefted. There were animals that had brains of respectable size, but they had no hands and that made all the difference. "

― Isaac Asimov , Foundation's Edge (Foundation #4)