become embodied in a maxim: Proceed from the known to the unknown.

A classic example of good educational practice in this connection is
the way in which Francis W. Parker, a progressive educator of a former
generation, taught geography. When he desired to show how water running
over hard rocky soil produced a Niagara, he took his class down to the
creek behind the school house, built a dam and allowed the water to
flow over it. When he wished to show how water flowing over soft ground
resulted in a deltoid Nile, he took the class to a low, flat portion of
the creek bed and pointed out the effect. The creek bed constituted an
old familiar element in the children's experience. Niagara and the Nile
described in terms of it were intelligible.

Naturally in modern educational practice it is not always possible to
have miniature waterfalls and river bottoms at hand, still it is
possible to follow this principle. When, in studying Mediaeval History,
you read a description of the guilds, do not regard them as distant,
cold, inert institutions devoid of significance in your life. Rather,
think of them in terms of things you already know: modern Labor Unions,
technical schools, in so far as the comparison holds good. Then trace
their industrial descendants down to the present time. By thus thinking
about the guilds, hitherto distant and uninteresting, you will begin to
see them suffused with meaning, alight with significance, a real part
of yourself. In short, you will have achieved interest.

There is still another psychological law of interest: _In order to
develop interest in a subject, exert activity toward it_. We see the
force of this law when we observe a man in the process of developing an
interest in golf. At the start he may have no interest in it whatever;
he may even deride it. Yielding to the importunities of his friends,