e. The processes of thought
become petrified in language. All progress in knowledge and
acquisition of new ideas is reflected in language by an increase of
words. But an examination of words in common use will show that they
are nearly all the names of concepts. Proper names are the principal
exception. Every common noun, verb, adjective, adverb, and preposition
is the name of a concept; for example, horse, beauty, to steal,
running, over, early, yellow, grape, ocean, etc. To understand these
concepts there must be somewhere a progress from the individual to the
abstract, an induction from particulars to a general concept.

Abstract or general notions cannot be acquired at first hand without
specific illustrations. Even where the deductive process is supposedly
employed, a closer examination will uncover the concrete or individual
illustrations in the background, and until these are reached the
concept has no clear meaning. The _concrete examples_, whether
introduced sooner or later by way of explanation, are the real basis of
the understanding of the concept. It is customary to invert the
inductive process and to drive it stern forwards through grammar,
geography, and other studies. Take, for example, the word boomerang as
it comes up in a geography or reading lesson. Webster's dictionary,
which is recommended to children as a first resort in such
difficulties, calls it "A remarkable missile weapon used by the natives
of Australia." This gives a faint notion by using the familiar word
_weapon_. The picture accompanying the word in the dictionary gives a
more accurate idea because nearer the concrete. The best possible
explanation would be a real boomerang thrown by a native South-Sea
Islander. In the absence of these, a picture and a vivid description
are the best means at our disposal. The common mistake is in learning
and reciting the definition while neglecting the concrete basis. By
way of further illustration, try to explain to children, who have never
heard of them before, the egg-plant, palm-tree, cactus, etc.

It would be of interest to inquire into the process of concept-building
in each of the _school studies_, where it appears under quite varying
forms. The natural sciences are perhaps the best examples of
concept-building from concrete materials, advancing regularly through a
series of concepts from the individuals and species to the most general
classes of plants, animals, etc. In chemi