njunctions of this experience.

This great source of error has been so abundantly illustrated under the
head of Passive Illusions that I need not dwell on it further. It is
plain that a passive error of perception, or of expectation, is due in
general to a defective grouping of elements, to a grouping which
answers, perhaps, to the run of the individual's actual experience, but
not to a large and complete common experience.[148] Similarly, an
illusory general belief is plainly a welding together of elements (here
concepts, answering to innumerable representative images) in
disagreement with the permanent connections of experience. Even a
passive illusion of memory, in so far as it involves a rearrangement of
successive representations, shows the same kind of defect.

In the second place, this incorrect grouping maybe due, not to defects
in attention and discrimination, combined with insufficiently grounded
association, but to the independent play of constructive imagination and
the caprices of feeling. This is illustrated in what I have called
Active Illusions, whether the excited perceptions and the hallucinations
of sense, or the fanciful projections of memory or of expectation. Here
we have a force directly opposed to that of experience. Active illusion
arises, not through the imperfections of the intellectual mechanism, but
through a palpable interference with this mechanism. It is a regrouping
of elements which simulates the form of a suggestion by experience, but
is, in reality, the outcome of the individual mind's extra-intellectual
impulses.

We see, then, that, in spite of obvious differences in the form, the
process in all kinds of immediate cognition is fundamentally identical.
It is essentially a bringing together of elements, whether similar or
dissimilar and associated by a link of contiguity, and a viewing of
these as connected parts, of a whole; it is a process of synthesis. And
illusion, in all its forms, is bad grouping or carelessly performed
synthesis. This holds good even of the simplest kinds of error in which
a presentative element is wrongly classed; and it holds good of those
more conspicuous errors of perception, memory, expectation, and compound
belief, in which representations connect themselves in an order not
perfectly answering to the objective order.

This view of the nature and causes of illusion is clearly capable of
being expressed in physical language. Bad grouping of psychical ele