void of aesthetic elements, manhood will
be lacking in artistic interests. It is in youth also that our
intellectual interests, such as love of reading, of the study of nature,
of mathematics, must be laid.

=Interests Must be Limited.=--While emphasizing the importance of
establishing a wide range of interests when educating a child, the
teacher must remember that there is danger in a child acquiring too wide
a range. This can result only in a dissipation of effort over many
fields. While this prevents narrowness of vision and gives versatility
of disposition, it may prevent the attainment of efficiency in any
department, and make of the youth the proverbial "Jack-of-all-trades."

A study of the feeling of interest has been made at this stage on
account of its close connection with the problem of attention, and in
fact with the whole learning process. An examination of the other
classes of feeling will be made at a later stage in the course.

CHAPTER XXV

SENSE PERCEPTION

=Sensation and Perception Distinguished.=--Sensation and perception are
two terms applied usually without much distinction of meaning to our
recognition of the world of objects. When, for instance, a man draws
near to a stove, he may say that it gives him a _sensation_ of heat, or
perhaps that he _perceives_ it to be hot. In psychology, however, the
term sensation has been used in two somewhat different meanings. By some
the term is used to signify a state of consciousness conditioned merely
upon the stimulation of a sense organ, as the eye, ear, etc., by its
appropriate stimulus. To others, however, sensation signifies rather a
mental image experienced by the mind as it reacts upon and interprets
any sensory impression. Perception, on the other hand, signifies the
recognition of an external object as presented to the mind here and now.

=Sensation Implies Externality.=--When, however, a sensory image, such
as smooth, yellow, cold, etc., arises in consciousness as a result of
the mind reacting when an external stimulus is applied to some sense
organ, it is evident that, at least after very early infancy, one never
has the image without at once referring it to some external cause. If,
for instance, a person is but half awake and receives a sound sensation,
he does not ask himself, "What mental state is _this_?" but rather,
"What is _that_?" This shows an evident tendency to refer our sensations
at once to an external cause, or indicates