and compares present and past
sense-perceptions. It is the final process in the production of that
marvel of the mind, the "idea."

The simple perception of a sensation unaccompanied by any other mental
process is something that never happens to an adult human being.

In the infant's mind the arrival of a sense-impression arouses only
a perception, a consciousness of the sense-impression. In the mind of
any other person it awakens not only this present consciousness but
also the _associated_ memories of past experiences.

[Sidenote: _The Indelible Impress_]

Upon the slumbering mind of the newborn babe the very first message
from the sense-organs leaves its exquisite but indelible impress. The
next sense-perception is but part of a state of consciousness, in
which the memory of the first sense-perception is an active factor.
This is a higher type of mental activity. It is a something other and
more complex than the mere consciousness of a sensory message and the
decision as to its source.

The moment, then, that we get beyond the first crude sense-perception
_consciousness consists not of detached sensory images but of "ideas,"
the complex product of present sense-perceptions, past sense-perceptions
and the mental processes known to psychology as association and
discrimination_.

[Sidenote: _How Ideas are Created_]

Every concrete conception or idea, such as "horse," "rose,"
"mountain," is made up of a number of associated properties. It has
mass, form and various degrees of color, light and shade. Every
quality it possesses is represented by a corresponding visual,
auditory, tactual or other sensation.

Thus, your first sense-perception of coffee was probably that of
_sight_. You perceived a brown liquid and your causal judgment
explained that this sense-perception was the result of something
outside of your body. Standing alone, this causal judgment meant very
little to you, so far as your knowledge of coffee was concerned. So
also the causal judgment that traced your sense of the smell of coffee
to some object in space meant little until it was added to and
associated with your eye-vision of that same point in space. And it
was only when the causal judgment explaining the _taste_ of coffee
was added to the other two that you had an "_idea_" of what coffee
really was.

When you look at a building, you receive a number and variety of
simultaneous sensations, all of which, by the exercise of a causal
judgme