ition by affecting the digestive process, so the
agreeable odors about us, even those of the perfumes, play an important
part in the economy of life.

324. The Sense of Sight. The sight is well regarded as the
highest and the most perfect of all our senses. It plays so common and so
beneficent a part in the animal economy that we scarcely appreciate this
marvelous gift. Sight is essential not only to the simplest matters of
daily comfort and necessity, but is also of prime importance in the
culture of the mind and in the higher forms of pleasure. It opens to us
the widest and the most varied range of observation and enjoyment. The
pleasures and advantages it affords, directly and indirectly, have neither
cessation nor bounds.

Apart from its uses, the eye itself is an interesting and instructive
object of study. It presents beyond comparison the most beautiful example
of design and artistic workmanship to be found in the bodily structure. It
is the watchful sentinel and investigator of the external world. Unlike
the senses of taste and smell we seem, by the sense of vision, to become
aware of the existence of objects which are entirely apart from us, and
which have no direct or material link connecting them with our bodies. And
yet we are told that in vision the eye is affected by something which is
as material as any substance we taste or smell.

[NOTE. "The higher intelligence of man is intimately associated with
the perfection of the eye. Crystalline in its transparency, sensitive
in receptivity, delicate in its adjustments, quick in its motions, the
eye is a fitting servant for the eager soul, and, at times, the truest
interpreter between man and man of the spirit's inmost workings. The
rainbow's vivid hues and the pallor of the lily, the fair creations of
art and the glance of mutual affection, all are pictured in its
translucent depths, and transformed and glorified by the mind within.
Banish vision, and the material universe shrinks for us to that which
we may touch; sight alone sets us free to pierce the limitless abyss
of space."--M'Kendrick and Snodgrass's _Physiology of the Senses_.]

Physicists tell us that this material, known as the _luminiferous ether_,
permeates the universe, and by its vibrations transmits movements which
affect the eye, giving rise to the sensation of light, and the perception
of even the most distant objects. Our eyes are so constructed