Most of man's organs can be utilized in more than one way. His hands can be used to grip and to push, his throat can serve to swallow and to expel, he uses his tongue to taste and to talk, his nose to breathe and to smell.

If each mode of activity required the use of a different organ, a man would have to be much more cumbersome than he now is, or he would have to give up doing some of the things of which he is now capable. He would need at least a score of hands if he needed one with which to grasp, another with which to lift, a third with which to push, a fourth with which to twist etc. Because he has only two, capable of doing twenty different things, he is much more compact and flexible than he otherwise would be.