of our senses, that we neglect to use the
senses themselves. If the graphometer measures the size of an angle
for us, we need not estimate it ourselves. The eye which measured
distances with precision intrusts this work to the chain; the steelyard
saves me the trouble of measuring weights by the hand. The more
ingenious our apparatus, the more clumsy and awkward do our organs
become. If we surround ourselves with instruments, we shall no longer
find them within ourselves.

But when, in making the apparatus, we employ the skill and sagacity
required in doing without them, we do not lose, but gain. By adding
art to nature, we become more ingenious and no less skilful. If,
instead of keeping a child at his books, I keep him busy in a workshop,
his hands labor to his mind's advantage: while he regards himself only
as a workman he is growing into a philosopher. This kind of exercise
has other uses, of which I will speak hereafter; and we shall see how
philosophic amusements prepare us for the true functions of manhood.

I have already remarked that purely speculative studies are rarely
adapted to children, even when approaching the period of youth; but
without making them enter very deeply into systematic physics, let all
the experiments be connected by some kind of dependence by which the
child can arrange them in his mind and recall them at need. For we
cannot without something of this sort retain isolated facts or even
reasonings long in memory.

In investigating the laws of nature, always begin with the most common
and most easily observed phenomena, and accustom your pupil not to
consider these phenomena as reasons, but as facts. Taking a stone, I
pretend to lay it upon the air; opening my hand, the stone falls.
Looking at Emile, who is watching my motions, I say to him, "Why did
the stone fall?"

No child will hesitate in answering such a question, not even Emile,
unless I have taken great care that he shall not know how. Any child
will say that the stone falls because it is heavy. "And what does
heavy mean?" "Whatever falls is heavy." Here my little philosopher is
really at a stand. Whether this first lesson in experimental physics
aids him in understanding that subject or not, it will always be a
practical lesson.

Nothing to be Taken upon Authority. Learning from the Pupil's own
Necessities.

As the child's understanding matures, other important considerations
demand that we choose his occu