passing by a lone graveyard interprets the
tall and slender shrub laden with white blossoms as a swaying ghost, the
misconception does not arise from any fault of mere vision, but from the
type of former knowledge which the other surroundings of the moment call
up, these evidently giving the mind a certain bias in its interpretation
of the sensuous, or colour, impressions.

=Perception in Adult Life.=--In our study of general method, sense
perception was referred to as the most common mode of acquiring
particular knowledge. A description of the development of this power to
perceive objects through the senses should, therefore, prove of
pedagogical value. But to understand how an individual acquires the
ability to perceive objects, it is well to notice first what takes place
in an ordinary adult act of perception, as for instance, when a man
receives and interprets a colour stimulus and says that he perceives an
orange. If we analyse the person's idea of an orange we find that it is
made up of a number of different quality images--colour, taste, smell,
touch, etc., organized into a single experience, or idea, and accepted
as a mental representation of an object existing in space. When,
therefore, the person referred to above says that he perceives an
orange, what really happens is that he accepts the immediate colour and
light sensation as a sign of the whole group of qualities which make up
his notion of the external object, orange, the other qualities essential
to the notion coming back from past experience to unite with the
presented qualities. Owing to this fact, any ordinary act of perception
is said to contain both presentative and representative elements. In the
above example, for instance, the colour would be spoken of as a
presentative element, because it is immediately presented to the mind in
sensuous terms, or through the senses. Anything beyond this which goes
to make up the individual's notion orange, and is revived from past
experience, is spoken of as representative. For the same reason, the
sensuous elements involved in an ordinary act of perception are often
spoken of as immediate, and the others as mediate elements of knowledge.

=Genesis of Perception.=--To trace the development of this ability to
mingle both presentative and representative elements of knowledge into a
mental representation, or idea, of an external object, it is necessary
to recall what has been noted regarding the relation of the ner