no time in school life when we can afford to cut loose from
the real world. There is scarcely a lesson in any subject that can not
be clarified and strengthened by calling in the fresh experiences of
daily life.

The discussion of the concept and of the inductive process has shown
that _concepts cannot be found at first hand_. There must be
observation of different objects, comparison, and grouping into a
class. A person who has never seen an elephant nor a picture of one,
can form no adequate notion of elephants in general. We can by no
shift dispense with the illustrations. The more the memory is filled
with vivid pictures of real things, the more easy and rapid will be the
progress to general truths. Not only are general notions of classes of
objects in nature, or of personal actions built up out of particulars,
but the general laws and principles of nature and of human society must
be observed in real life to be understood. We should have no faith in
_electricity_ if it were simply a scientific theory, if it had not
demonstrated its power through material objects. The idea of
_cohesion_ would never have been dreamed of, if it had not become
necessary to explain certain physical facts. The spherical form of the
earth was not accepted by many even learned men until sailors with
ships had gone around it. Political ideas of popular government which
a few centuries ago were regarded as purely utopian are now accepted as
facts because they have become matters of common observation. The
_circulation of the blood_ remained a secret for many centuries because
of the difficulties of bringing it home to the knowledge of the senses.
These examples will show how difficult it is to go beyond the reach of
sense experience. Even those philosophers who have tried to construct
theories without the safe foundation of facts have labored for naught.
The more our thought is checked and guided by nature's realities the
less danger of inflation with pretended knowledge. Bacon found that in
this tendency to theorize loosely upon a slender basis of facts was the
fundamental weakness of ancient philosophy. Nature if observed will
reiterate her truths till they become convincing verities, while the
study of words and books alone produces a _quasi-knowledge_ which often
mistakes the symbol for the thing.

Having this thought in mind, _Comenius_, more than two and a half
centuries ago, said, "It is certain that there is nothing i