own effort, he employs his own reason, not that
of another. Most of our mistakes arise less within ourselves than from
others; so that if he is not to be ruled by opinion, he must receive
nothing upon authority. Such continual exercise must invigorate the
mind as labor and fatigue strengthen the body.

The mind as well as the body can bear only what its strength will
allow. When the understanding fully masters a thing before intrusting
it to the memory, what it afterward draws therefrom is in reality its
own. But if instead we load the memory with matters the understanding
has not mastered, we run the risk of never finding there anything that
belongs to it.

Emile has little knowledge, but it is really his own; he knows nothing
by halves; and the most important fact is that he does not now know
things he will one day know; that many things known to other people he
never will know; and that there is an infinity of things which neither
he nor any one else ever will know. He is prepared for knowledge of
every kind; not because he has so much, but because he knows how to
acquire it; his mind is open to it, and, as Montaigne says, if not
taught, he is at least teachable. I shall be satisfied if he knows how
to find out the "wherefore" of everything he knows and the "why" of
everything he believes. I repeat that my object is not to give him
knowledge, but to teach him how to acquire it at need; to estimate it
at its true value, and above all things, to love the truth. By this
method we advance slowly, but take no useless steps, and are not
obliged to retrace a single one.

Emile understands only the natural and purely physical sciences. He
does not even know the name of history, or the meaning of metaphysics
and ethics. He knows the essential relations between men and things,
but nothing of the moral relations between man and man. He does not
readily generalize or conceive of abstractions. He observes the
qualities common to certain bodies without reasoning about the
qualities themselves. With the aid of geometric figures and algebraic
signs, he knows something of extension and quantity. Upon these
figures and signs his senses rest their knowledge of the abstractions
just named. He makes no attempt to learn the nature of things, but
only such of their relations as concern himself. He estimates external
things only by their relation to him; but this estimate is exact and
positive, and in it fancies and conve