ding, yet always preserving its circular form, according as the
brilliance is excessive or deficient; how the humours or lenses are
continually varying in figure and relative position so as to concentrate
every pencil of light admitted on that point exactly where the retina is
spread out to receive it; how, according as the object looked at is near
at hand or far off, certain muscles perform quite opposite services,
rendering the cornea more or less prominent, pushing the crystalline
lens forward or backward, and thereby lengthening or shortening the axis
of vision, so that, whether the rays enter divergently from a near
object, or parallel from a remote one, they equally fall into focus at
the same distance beyond, and equally form on the retina a picture of
the object from which they come, perhaps compressing a landscape of five
or six square leagues into a space of half an inch diameter, and anon
allowing the page of a book or a dinner-plate to occupy the entire field
of vision--to these and to any kindred marvels it would be superfluous
more than momentarily to refer. Suffice it to note how measureless the
superiority, as a mere piece of mechanism, of an average eye to the
finest of telescopes, and how just, nevertheless, is the
telescope-maker's claim to praise for skilful adaptation to the laws of
optics, when he has succeeded in a faint and feeble imitation of some
minor part of nature's visual apparatus. Yet nature's original and
infinitely more beautiful aptitudes we are forbidden to deem
adaptations, being required instead to regard them as self-produced, or,
at any rate, as having been undesigned. Now I unreservedly admit that,
among all conceivable forms, among the most exquisitely beautiful and
most usefully intricate and complex, there is not one which may not
possibly have been produced without aim or purpose by the mere
restlessness of elemental forces; the amount of probability of their
having been so produced being, however, according to the formula already
set forth in its proper place, as one to infinity multiplied more or
less frequently by itself. But what adequate superlative shall we invent
to express the credulity, the credulosity run mad, of those who, in a
matter of scientific belief, deliberately accept such odds. Observe how
at once extravagantly gratuitous and painfully elaborate such
credulosity is; how easily, on the one hand, all its ends could be
served by the simple expedient of supposin