Page:Labour and childhood.djvu/127

 and finally in modern days appeared to find a soul and to develop in a way that must either lift us up into a higher kind of life or destroy us for ever.

Every school boy knows that there are three kinds of levers in the body. The first is that in which the moving point is between the power and the weight —as, for example in the head, or rather in the skull, which is placed so that the face can be raised freely at one end, and the back of the head at another. Among levers of this order are the see-saw, the balance and some kinds of crowbar, and many examples of this kind of lever are, as we should expect, to be found in very old mechanisms— such as the "shadoof"—a pillar of Nile mud with a swing beam and a bucket which a man dipped into the water. A lever of the second order is to be found in the lifted foot, and its projection in the homely wheelbarrow or in a crowbar when used for lifting a weight while one of its ends rests on the ground.

There is yet one other order of lever which may be studied in the lifting of the forearm, in the straightening of a limb after bending, and in the treadle of a machine. All these were projected long ago. But the body did not yield up all its secrets— and will never do so, since it is always creating a new mystery.