their
causal connection with each other and the role that each plays in the
economy of the whole. The causal series thus clearly outlined produces
insight into an occupation, while every typical machine or appliance is
one of a cross series intercepting the original series. The
acquisition and assimilation of knowledge in different subjects will be
found to exhibit the mental states of absorption and reflection as just
illustrated. Observe the manner in which we study a poem. It is first
read and interpreted sentence by sentence, glancing from verse to verse
to get the connections. When the whole piece has been read and
understood in its parts and connections, the suggested lines of thought
are taken up and followed out in their wider applications. Take for
example the "Burial of Moses," and in the proper analysis and study of
the poem, such a process of absorption and reflection is observable.
In tracing the biography of John Quincy Adams or of Alexander Hamilton,
the facts of personal experience and action first absorb the attention
from step to step in the study of his life. But reflection on the
bearings of these personal events, upon contemporaries, and upon public
affairs is noticed all along. The same mental process is observed in
studying a battle in history, a sentence in grammar, a squirrel in
natural history, or a picture in art.

The effect of such mental absorption and reflection is to build up
_concepts_. Series of causally related parts are also formed, but each
series in the end becomes a more complete complex concept; that is, a
representative of many similar series. The inspection of one printing
establishment suggests others which are brought into comparison till
the general notion, publishing-house, is more clearly conceived. The
same is true in the lumber trade. The concept lumber-business is not
confined to Minneapolis or Chicago, but is common to the great lake
region, Maine, Washington, Norway, and other countries. Concepts
become more varied and complex with the advance of studies, and there
is scarcely anything we learn by observation or reflection that does
not ultimately illustrate and build up our concepts. The observation
of even the miscellaneous objects in a large city leads to a variety of
concepts, and in the end, by comparison, to the general notion, _city_.

How strong the concept-creating tendency of all experience and thought
is, can be seen in the _words_ of languag