but have we nothing but arms and legs? Have
we not eyes and ears as well? and are they of no use while the others
are employed? Use, then, not only your bodily strength, but all the
senses which direct it. Make as much of each as possible, and verify
the impressions of one by those of another. Measure, count, weigh, and
compare. Use no strength till after you have calculated the resistance
it will meet. Be careful to estimate the effect before you use the
means. Interest the child in never making any useless or inadequate
trials of strength. If you accustom him to forecast the effect of
every movement, and to correct his errors by experience, is it not
certain that the more he does the better his judgment will be?

If the lever he uses in moving a heavy weight be too long, he will
expend too much motion; if too short, he will not have power enough.
Experience will teach him to choose one exactly suitable. Such
practical knowledge, then, is not beyond his years. If he wishes to
carry a burden exactly as heavy as his strength will bear, without the
test of first lifting it, must he not estimate its weight by the eye?
If he understands comparing masses of the same material but of
different size, let him choose between masses of the same size but of
different material. This will oblige him to compare them as to
specific gravity. I have seen a well-educated young man who, until he
had tried the experiment, would not believe that a pail full of large
chips weighs less than it does when full of water.

The Sense of Touch.

We have not equal control of all our senses. One of them, the sense of
touch, is in continual action so long as we are awake. Diffused over
the entire surface of the body, it serves as a perpetual sentinel to
warn us of what is likely to harm us. By the constant use of this
sense, voluntary or otherwise, we gain our earliest experience. It
therefore stands less in need of special cultivation. We observe
however, that the blind have a more delicate and accurate touch than
we, because, not having sight to guide them, they depend upon touch for
the judgments we form with the aid of sight. Why then do we not train
ourselves to walk, like them, in the dark, to recognize by the touch
all bodies we can reach, to judge of objects around us, in short, to do
by night and in the dark all they do in daytime without eyesight? So
long as the sun shines, we have the advantage of them; but they can