Year: 1878

The following is from a review of DR..
Clark's "Vision,'' in the atlantic
Mcmtblu:


The natural desire and expectation of
the reader is that the functions of the
eye, or of the brain, should be made as
clear to him as the operations of a clock
or of the phonograph. But there is this
difficulty in the case of the functions of
the nervous system: that we have to do
with phenomena of which our senses
are incapable of taking cognizance, ex-
cept in the way of consciousness. An
example will perhaps make more clear
what is meant. Electricity is vaguely
familiar to all as a mighty, omnipresent
power, which in one form or another is
everywhere and at all times exerting
great influence and producing immense
effects. Yet it trarely comes under our
direct observation; until modern times
its existence, even, was hardly suspect
ed. Men have lived in the midst of it,
surrounded and pervaded by its subtle
influence, yet seeing it, feeling it, hear
ing it not, except when stroke of light
ming, shifting eye and ear, would bring
the hidden power within the limited
scope of their senses. Electricity eludes
our recognition as long as it remains
electricity. We detect its presence only
when, by transformation of forces, it
is changed into some other force, such
as heat, light, sound, or motion, of which
we can take cognizance through the
channel of one of our senses. This is
the reason why our knowledge of elec-
tricity has been of such slow growth
that it is only within the present century
that man has learned to use this mighty,


unseen force, to direct it here and there,


and make it do his work. But. although


our mastery over it, as exemplified, for


instance. in its latest and most striking


application, the telephone, is so won


derful, we still remain in utter igno-


rance Of electricity per Sc. We only


know it when transmitted into force


which we have senses to perceive. Thus


in the telephone the mysterious invisi-


BILE force which traverses the conducting


wire, when transformed by an ingenious


device into sound, becomes appreciable


to our ear. @


Such is also, in q measure, the case
with the operations of the nervous sys-
tenn. Here, besides our five senses with
which to investigate the phenomena,
we have one additional sense, so to
speak, namely consciousness, which is
the source of by far the greater part of
what we know concerning our senses
themselves and the operations of the
mind. But, except in so far as the
phenomena in question are subject to
consciousness, or are amenable to in
vestigation by sight, hearing, touch,
taste, or smell, we are, and mr.st ever
remain, ignorant of them. With regard
to sight, in particular, we know that the
first step in the process is the impact of
rays of light focused upon the retina,
and that the last step is consciousness
OF vision. We know what organs, some
composed of fibers, others of cells, are
traversed by the subtle influence, or
stimulus, originated in the retina by the |
rays of light But what it is that is so
transmitted through the nerve fibers and
cells, and finally begets consciousness of
vision in the gray matter of the convolu-
tions, we do not know, and never shall
know, whatever further progress may
be achieved in histology and in biolog-
ical chemistry. The stimulus is some |
thing that we can neither see, nor hear,
nor feel, nor taste. nor smell. just as
when electricity travels along q wire we
are unaware of its presence, till, assum-
ing another shape not its own, it betrays I
itself by a visible spark, or by the audi |
BILE and visible motion of q lever, 50 we
are unable by any device to become
cognizant of the stimulus proceeding
along sentient nerve toward the brain,
until, on reaching its destination, the
stimulus is transmitted into a motor i'm
pulse whereby visible muscular con-
traction is excited, or into the inscruta-
BILE phenomenon known to us as con-
sciousness. To our senses and to con-
sciousness we owe all the knowledge
that we possess, both of the inner and
of the outer world, of the ego and of the
non-ego.