ion, both press back the crystalline lens nearer the retina, and
also flatten it; the vitreous humor, in which the crystalline lens lies,
a fine, transparent humor, about as thick as the white of an egg, giving
way behind it, and also slightly altering its form and power of
refraction to suit the case. Thus, that which the astronomer, or the
microscopist, performs by a tedious process, and then very imperfectly,
we perform perfectly, easily, instantly, and almost involuntarily, with
that perfect compound microscope and telescope invented by the Former of
the human eye. Surely, in giving us an instrument so admirably fitted
for observing the lofty grandeur of the heavens and the lowlier beauties
of the earth, he meant to allure us to the discovery of the perfections
of the great Designer and Former of all these wondrous works.

But there is another contrivance in the eye, adapted to lead us further
to the consideration of the extent of the knowledge of its power. We are
placed in a world of variable lights, of day and night, and of all the
variations between light and darkness. We can not see in the full blaze
of light, nor yet in utter darkness. Had the eye been formed to bear
only the noonday glare, we had been half blind in the afternoon, and
wholly so in the evening. If the eye were formed so as to see at night,
we had been helpless as owls in the day. But the variations of light in
the atmosphere may be in some measure compensated, as we know, by
regulating the quantity admitted to our houses--shutting up the windows.
When we wish to regulate the admission of light to our rooms, we have
recourse to various clumsy contrivances; paper blinds, perpetually
tearing, sunblind rollers that will not roll, venetian blinds
continually in need of mending, awnings blowing away with every storm,
or shutters, which shut up and leave us in entire darkness. A
self-acting window, which shall expand with the opening of light in the
mornings and evenings, and close up of its own accord as the light
increases toward noon, has never been manufactured by man. But the
Former of the eye took note of the necessities and conveniences of the
case, and besides giving a pair of shutters to close up when we go to
sleep, he has given the most admirable sunblinds ever invented. The
nerve of the eye at the back of its chamber can not see without light,
and its light comes through the little round window called the pupil, or
black of the eye--which i