vous
system to our conscious acts. When the young child first comes in
contact with the world of strange objects with which he is surrounded,
the impressions he receives therefrom will not at first have either the
definite quality or the relation to an external thing which they later
secure. As a being, however, whose first tendencies are those of
movement, he grasps, bites, strokes, smells, etc., and thus goes out to
meet whatever his surroundings thrust upon him. Gradually he finds
himself expand to take in the existence of a something external to
himself, and is finally able, as the necessary paths are laid down in
his nervous system, to differentiate various quality images one from the
other; as, touch, weight, temperature, light, sound, etc. This will at
once involve, however, a corresponding relating, or synthetic, attitude
of mind, in which different quality images, when experienced together as
qualities of some vaguely felt thing, will be organized into a more or
less definite knowledge, or idea, of that object, as illustrated in the
figure below. As the child in time gains the ability to _attend_ to the
sensuous presentations which come to him, and to discriminate one
sensation from another, he discovers in the vaguely known thing the
images of touch, colour, taste, smell, etc., and finally associates them
into the idea of a better known object, orange.

[Illustration: A. Unknown thing. B. Sensory stimuli. C. Sensory images.
D. Idea of object.]

=Control of Sensory Image as Sign.=--Since the various sense impressions
are carried to the higher centres of the brain, they will not only be
interpreted as sensory images and organized into a knowledge of external
objects, but, owing to the retentive power of the nervous tissue, will
also be subject to recall. As the child thus gains more and more the
ability to organize and relate various sensory images into mental
representations, or ideas, of external objects, he soon acquires such
control over these organized groups, that when any particular sensation
image out of a group is presented to the mind, it will be sufficient to
call up the other qualities, or will be accepted as a sign of the
presence of the object. When this stage of perceptual power is reached,
an odour coming from the oven enables a person to perceive that a
certain kind of meat is within, or a noise proceeding from the tower is
sufficient to make known the presence of a bell. To possess the ability