ions.

In this way, our dream-life touches that childish condition of the
intelligence which marks the decadence of old age and the encroachments
of mental disease. The parallelism between dreams and insanity has been
pointed out by most writers on the subject. Kant observed that the
madman is a dreamer awake, and more recently Wundt has remarked that,
when asleep, we "can experience nearly all the phenomena which meet us
in lunatic asylums." The grotesqueness of the combinations, the lack of
all judgment as to consistency, fitness, and probability, are common
characteristics of the short night-dream of the healthy and the long
day-dream of the insane.[100]

But one great difference marks off the two domains. When dreaming, we
are still sane, and shall soon prove our sanity. After all, the dream of
the sleeper is corrected, if not so rapidly as the illusion of the
healthy waker. As soon as the familiar stimuli of light and sound set
the peripheral sense-organs in activity, and call back the nervous
system to its complete round of healthy action, the illusion disappears,
and we smile at our alarms and agonies, saying, "Behold, it was a
dream!"

On the practical side, the illusions and hallucinations of sleep must be
regarded as comparatively harmless. The sleeper, in healthy conditions
of sleep, ceases to be an agent, and the illusions which enthral his
brain have no evil practical consequences. They may, no doubt, as we
shall see in a future chapter, occasionally lead to a subsequent
confusion of fiction and reality in waking recollection. But with the
exception of this, their worst effect is probably the lingering sense of
discomfort which a "nasty dream" sometimes leaves with us, though this
may be balanced by the reverberations of happy dream-emotions which
sometimes follow us through the day. And however this be, it is plain
that any disadvantages thus arising are more than made good by the
consideration that our liability to these nocturnal illusions is
connected with the need of that periodic recuperation of the higher
nervous structures which is a prime condition of a vigorous intellectual
activity, and so of a triumph over illusion during waking life.

For these reasons dreams may properly be classed with the illusions of
normal or healthy life, rather than with those of disease. They
certainly lie nearer this region than the very similar illusions of the
somnambulist, which with respect to their origin appe