n in the recalling
of near events.

So much as to the extent of illusion as brought to light by our
preceding study. Let us now glance at the conclusions obtained
respecting its nature and its causes.

_Causes of Illusion._

Looking at illusion as a whole, and abstracting from the differences of
mental mechanism in the processes of perception, memory, etc., we may
say that the _rationale_ or mode of genesis of illusion is very much the
same throughout. Speaking broadly, one may describe all knowledge as a
correspondence of representation with fact or experience, or as a stable
condition of the representation which cannot be disturbed by new
experiences. It does not matter, for our present purpose, whether the
fact represented is supposed to be directly present, as in presentative
cognition; or to be absent, either as something past or future, or
finally as a "general fact," that is to say, the group of facts (past
and future) embodied in a universal proposition.[147]

In general this accordance between our representations and facts is
secured by the laws of our intellectual mechanism. It follows from the
principles of association that our simple experiences, external and
internal, will tend to reflect themselves in perception, memory,
expectation, and general belief, in the very time-connections in which
they actually occur. To put it briefly, facts which occur together will
in general be represented together, and they will be the more perfectly
co-represented in proportion to the frequency of this concurrence.

Illusion, as distinguished from correct knowledge, is, to put it
broadly, deviation of representation from fact. This is due in part to
limitations and defects in the intellectual mechanism itself, such as
the imperfections of the activities of attention, discrimination, and
comparison, in relation to what is present. Still more is it due to the
control of our mental processes by association and habit. These forces,
which are at the very root of intelligence, are also, in a sense, the
originators of error. Through the accidents of our experience or the
momentary condition of our reproductive power, representations get
wrongly grouped with presentations and with one another; wrongly
grouped, that is to say, according to a perfect or ideal standard,
namely, that the grouping should always exactly agree with the order of
experience as a whole, and the force of cohesion be proportionate to the
number of the co