grades, as they advance from the normal and familiar to the undeniably
startling. At the same time an account of the current theories of
Apparitions is offered, in language as free from technicalities as
possible. According to modern opinion every "ghost" is a
"hallucination," a false perception, the perception of something which
is not present.

It has not been thought necessary to discuss the psychological and
physiological processes involved in perception, real or false. Every
"hallucination" is a perception, "as good and true a sensation as if
there were a real object there. The object happens _not_ to be there,
that is all." {0a} We are not here concerned with the visions of
insanity, delirium, drugs, drink, remorse, or anxiety, but with
"sporadic cases of hallucination, visiting people only once in a
lifetime, which seems to be by far the most frequent type". "These,"
says Mr. James, "are on any theory hard to understand in detail. They
are often extraordinarily complete; and the fact that many of them are
reported as _veridical_, that is, as coinciding with real events, such
as accidents, deaths, etc., of the persons seen, is an additional
complication of the phenomenon." {0b} A ghost, if seen, is undeniably
so far a "hallucination" that it gives the impression of the presence
of a real person, in flesh, blood, and usually clothes. No such
person in flesh, blood, and clothes, is actually there. So far, at
least, every ghost is a hallucination, "_that_" in the language of
Captain Cuttle, "you may lay to," without offending science, religion,
or common-sense. And that, in brief, is the modern doctrine of
ghosts.

The old doctrine of "ghosts" regarded them as actual "spirits" of the
living or the dead, freed from the flesh or from the grave. This