assimilation go on without conscious effort? If
kept in a healthy state the organs of digestion are self active. Not
so the mind. Ideas entering the mind are not so easily assimilated as
the food materials that enter the stomach. A cow chews her cud once,
but the ideas that enter our minds may be drawn from their receptacle
in the memory and worked over again and again. Ideas have to be put
side by side, separated, grouped, and arranged into connected series.
There is, no doubt, some tendency in the mind toward involuntary
assimilation, but it greatly needs culture and training. Many people
never reach the _thinking_ stage, never learn to survey and reflect.
The tendency of the mind to work over and digest knowledge should
receive ample culture in the schools. There is a mental inertia
produced by pure memory exercise that is unfavorable to reflection. It
requires an extra exertion to arrange and organize facts even after
they are acquired. But when the habit of reflection has been
inaugurated it adds much interest and value to all mental acquisitions.

There are also well-established principles which guide the mind in
elaborating its facts. The _laws of the association_ of ideas indicate
clearly the natural trend of mental elaboration. The association of
things because of contiguity in time and place is the simplest mode.
The classification of objects or activities on the basis of
resemblance, is the second form and that upon which the inductive
process is principally founded. In the third case objects and series
are easily retained in memory when the relation of cause and effect is
perceived between them. These natural highways of association,
especially the second and third, should be frequently traveled in
linking the facts of school study with each other. Indeed the outcome
of a rational survey of an object or fact in its different relations is
an association of ideas which is one of the best results of study.
Such connections of resemblance and difference or of cause and effect
are abundant and interesting in the natural sciences and physical
geography, also in history and languages.

The Herbartians draw an important distinction between _psychical_ and
_logical_ concepts or general notions. The _psychical_ concept is
worked out naturally by a child or an adult as a result of the chance
experiences of life. It is usually a work of accident; is incomplete,
faulty, and often misleading. The _logica