in the sensory ganglia, and
the evidences of memory appear. The first token of this is perhaps the
display of an attachment to persons, not through any intelligent
recognition of relationship, but merely because of familiarity. This is
followed by the manifestation of a liking to accustomed places and a
dread of strange ones. At this stage the infant is leading an
instinctive life, and has made no greater advance than many of the lower
mammals; but they linger here, while he proceeds onward. He soon shows
high powers of memory, the exercise of reason in the determinations of
judgment, and in the adaptation of varied means to varied ends.

Such is therefore the process of development of the nervous system of
man; such are the powers which consequently he successively displays.
His reason at last is paramount. No longer are his actions exclusively
prompted by sensations; they are determined much more by ideas that have
resulted from his former experiences. While animals which approach him
most closely in construction require an external stimulus to commence a
train of thought, he can direct his mental operations, and in this
respect is parted from them by a vast interval. The states through which
he has passed are the automatic, the instinctive, the intellectual; each
has its own apparatus, and all at last work harmoniously together.

[Sidenote: Every person consists of two lateral individuals.] But
besides this superposition of an instinctive apparatus upon an automatic
one, and an intellectual upon an instinctive, the nervous system
consists of two equal and symmetrical lateral portions, a right half and
a left. Each person may be considered as consisting in reality of two
individuals. The right half may be stricken with palsy, the left be
unimpaired; one may lose its sight or hearing, the other may retain
them. These lateral halves lead independent lives. Yet, though
independent in this sense, they are closely connected in another. The
brain of the right side rules over the left half of the body, that of
the left side rules over the right of the body. [Sidenote: Consequences
of this doubleness of construction.] On the relationships and
antagonisms of the two halves of the cerebro-spinal system must be
founded our explanations of the otherwise mysterious phenomena of double
and alternate life; of the sentiment of pre-existence; of trains of
thought, often double, but never triple; of the wilful delusions of
castle-buil