Читать книгу Fables of Infidelity and Facts of Faith - Robert Patterson - Страница 6

Let us now turn our thoughts to the instrument of sight. The optic nerve is the part of the eye which conveys visions to the mind. Suppose, instead of being where you observe it, at the back part of the eye, it had been brought out to the front, and that reflections from objects had fallen directly upon it. It is obvious that it would have been exposed to injury from every floating particle of dust, and you would always have felt such a sensation as is caused by a burn or scald when the skin peels off, and leaves the ends of the nerves exposed to the air. The tender points of the fibers of the optic nerve, too, would soon become blunted and broken, and the eye, of course, useless. How, then, is the nerve to be protected, and yet the sight not obstructed? If it were covered with skin, as the other nerves are, you could not see through it. For thousands of years after men had eyes and used them, they knew no substance, at once hard and transparent, which could answer the double purpose of protection and vision. And to this day they know none hard enough for protection, clear enough for vision, and elastic enough to resume its form after a blow. But men did the best they could, and put a round piece of brittle but transparent glass in a ring of tougher metal for the protection of the hands of a watch; and he who first invented the watch crystal thought he had made a discovery. Now, observe in the eye, that forward part is the watch glass; the cornea, made of a substance at once hard, transparent and elastic—which man has never been able to imitate—set into the sclerotica, that white, muscular coat which constitutes the white of your eye, acts as a frame for the cornea, and answers another important purpose, as we shall presently see.

But, supposing the end of the nerve protected by the glass, we might have had it brought up to the glass without any interposing lenses or humors, as, in fact, is nearly the case with some crustacea. We can not well imagine all the inconveniences of such an eye to us. If we could see distinctly at all, we could not see much farther or wider than the breadth of the end of the nerve at once. Our sight would then be very like that faculty of perceiving colors by the points of the fingers, which some persons are said to possess. In that case, seeing would only be a nicer kind of groping, and our eyes would be more conveniently fixed on the points of our fingers; or, as with many insects, on the ends of long antennae. Such a form of eye is precisely suited to the wants of an animal which has not an idea beyond its food, which has no business with any object too large for its mouth, and whose great concern is to stick to a rock and catch whatever animalculæ the water floats within the grasp of its feelers. But for a being whose intercourse should be with all the works of God, and whose chief end in such intercourse should be to behold the Creator reflected in his works, it was manifestly necessary to have a wider and larger range of vision; and, therefore, a different form of eye. Both these objects, breadth of field combined with length of range, are obtained by placing the optic nerve at the back of the eye, and interposing several lenses, through which objects are observed. By this arrangement a visual angle is secured, and all objects lying within it are distinctly visible at the same time. This faculty of perceiving several objects at the same time is a special property of sight which tends greatly to enlarge our conceptions of the knowledge of Him who gave it. A man who never saw can have no idea of it. He can not taste two separate tastes at once, nor smell two distinct smells at once; nor feel more than one object with each hand at once; and if he hears several sounds at the same time, they either flow into each other, making a harmony, or confuse him with their discord. Yet we are all conscious that we see a vast variety of distinct and separate objects at one glance of our eyes. I think it is manifest that the Former of such an eye not only intended its owner to observe such a vast variety of objects, but from the capacity of his own sight to infer the vastly wider range of vision of Him who gave it.

Besides the breadth of the field of vision, we also require length of range for the purpose of life. The thousand inconveniences which the short-sighted man so painfully feels are obvious to all. Yet it may tend to reconcile such to their lot to know that thousands of the liveliest and merriest of God's creatures can not see an inch before them. Small birds and insects, which feed on very minute insects, need eyes like microscopes to find them; while the eagle and the fish hawk, which soar up till they are almost out of sight, can distinctly see the hare or the herring a mile below them, and so must have eyes like telescopes. We, too, need to observe minute objects very closely, as when we read fine print, or when a lady threads a fine needle at microscope range; but, if confined to that range, we could not see our friends across the room, or find our way to the next street. Again, in traveling we need to see objects miles away, and at night we see the stars millions of miles away; but then, if confined to the long range, we should be strangers at home, and never get within a mile of any acquaintance. Now, how to combine these two powers, of seeing near objects and distant ones with the same eye, is the problem which the Maker of the eye had to solve. Let us look how man tried to solve it. A magnifying lens will collect the rays from any distant object, and convey them to a point called the focus. Then suppose we put this glass in the tube of an opera-glass, or pocket spy-glass, and look through the eye-hole and the concave lens, properly adjusted, in front of it, we shall see the image of the object considerably magnified. But suppose the object draws very near, we see nothing distinctly; for the rays reflected from it, which were nearly parallel while it was at a distance, are no longer so when it comes near, but scatter in all directions, and those which fall on the lens are collected at a point much nearer to the lens than before, and the eye-glass must be pushed forward to that focus. Accordingly, you know that the spy-glass is made to slide back and forward, and the telescope has a screw to lengthen or shorten the tube according to the distance of the objects observed. Another way of meeting the case would be by taking out the lens, and putting in one of less magnifying power, a flatter lens, for the nearer object. Now, at first sight, it would seem a very inconvenient thing to have eyes drawing out and in several inches like spy-glasses, and still more inconvenient to have twenty or thirty pairs of eyes, and to need to take out our eyes, and put in a new set twenty times a day. The ingenuity of man has been at work hundreds of years to discover some other method of adapting an optical instrument to long and short range, but without success. Now, the Former of the eye knew the properties of light and the properties of lenses before the first eye was made; he knew the mode of adjusting them for any distance, from the thousands of millions of miles between the eye and the star, to the half-inch distance of the mote in the sunbeam; and he had not only availed himself of both the principles which opticians discovered, but has executed his work with an infinite perfection which bungling men may admire, but can never imitate. The sclerotic coat of the eye, and the choroid which lies next it are full of muscles which, by their contraction, 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 is simply a hole in the iris, or colored part. Now this iris is formed of two sets of muscles: one set of elastic rings, which, when left to themselves, contract the opening; and another set at right angles to them, like the spokes of a wheel, pulling the inner edge of the iris in all directions to the outside. In fact it is not so much a sunblind, as a self-acting window, opening and closing the aperture according to our need of light, and doing this so instantaneously that we are not sensible of the process.

It is self-evident that the Maker of such an eye was acquainted with the properties of light, and the alternations of night and day, as well as with the mechanical contrivances for adjusting the eye to these variable circumstances. He has given us an eye capable of seeking knowledge among partial darkness, and of availing itself for this purpose of imperfect light; an apt symbol of our mental constitution and moral situation in a world where good and evil, light and darkness, mix and alternate.

Perhaps some one is ready to ask, What is the use of so many lenses in the eye? It seems as if the crystalline lens and the optic nerve were sufficient for the purpose of sight, with the cornea simply to protect them. What is the use of the aqueous humor and the vitreous humor?

Light, when refracted through the lens, becomes separated into its component colors—red, yellow, green, blue, and violet; and the greater the magnifying power of the lens, and the brighter the object viewed, the greater the dispersion of the rays. So that if the crystalline lens of the eye alone were used, we should see every white object bluish in the middle, and yellowish and reddish at the edges; or, in vulgar language, we should see starlight.

This difficulty perplexed Sir Isaac Newton all his life, and he never discovered the mode of making a refracting telescope which would obviate it. But M. Dolland, an optician, reflecting that the very same difficulty must have presented itself to the Maker of the eye, determined to ascertain how he had obviated it. He found that the Maker of the eye had a knowledge of the fact that different substances have different powers of refracting or bending the rays of light which pass through them, and that liquids have generally a different power of refraction from solids. For instance, if you put a straight stick in water, the part under water will seem bent at a considerable angle, while if you put the stick through a little hole in a pane of glass it will not seem so much bent. He further discovered that oil of cassia had a different power of refraction from water, and the white of an egg still a different power. He discovered also that the first lens of the eye, the aqueous humor, is very like water; that the crystalline lens is a firm jelly, and that the vitreous humor is about the consistency of the white of an egg. The combination of these three lenses, of different powers of refraction, secures the correction of their separate errors. He could not make telescope lenses of jelly, nor water; therefore, he could not make a perfect achromatic telescope, but he learned the lesson of mutual compensations of difficulties which the Maker of the eye teaches the reflecting anatomist, and procuring flint and crown glass of different degrees of refraction, he arranged them in the achromatic lens so as nearly to remedy the defect.

I think that you will at once admit that Dolland's attempt to remedy the evils of confused sight in the telescope indicated a desire to obtain a precise and correct view of the objects; and that his success in constructing an instrument, nearly perfect, for the use of astronomers, gave evidence that he himself had a clear idea of that perfect and accurate vision which he thus attempted to bestow on them. Shall we then imagine any inaccuracy in the sight of Him, who not only desired, but executed and bestowed on us, an instrument so perfectly adapted to the imperfections of this lower world, and whose very imperfections are the materials from which he produces clear and perfect vision? No! in God's eye there are no chromatic refractions of passions, or prejudice, or party feeling, or self-love. He sees no reflected or refracted light. O Father of Light! with whom is no variableness, or shadow of turning, open our eyes to behold Thee clearly!

Our text thus leads us to a knowledge of God's character, from the structure of the bodies he has given us. He that formed my eye sees. Though my feeble vision is by no means a standard or limit for his Omniscience, yet I may conclude that every perfection of the power of sight he has given me existed previously in him. Has he endowed me, a poor puny mortal, the permanent tenant of only two yards of earth, with an eye capable of ranging over earth's broad plains and lofty mountains, of traversing her beauteous lakes and lovely rivers, of scanning her crowded cities, and inspecting all their curious productions, and specially delighting to investigate the bodily forms of men, and their mental characters displayed on the printed page? Has he given me the principle of curiosity, without which such an endowment were useless? Then most undoubtedly he has Himself both the desire to observe all the works of his hands, and the power to gratify that desire. The Former of the eye must of necessity be the great Observer.

Wheresoever an eye is found of his handiwork, and wheresoever sight is preserved by his skill, let the owner of such an instrument know that if he can see, God can, and as surely as he sees, God does.

If it is possible for us to behold many objects distinctly at once, it is not impossible for God to behold more. If he has given us an eye to look from earth to heaven, then his eye sees from heaven to earth. If I can see accurately, God's inspection is much more impartial. And if he has given me the power of adjusting my imperfect vision to the varying lights and shades of this changing scene, let me not dream for a moment that he is destitute of a corresponding power of investigating difficulties, and penetrating darknesses, and bringing to light hidden works and secret things. God is light. In him is no darkness at all. Neither is there any creature that is not manifest in his sight, but all things are naked and opened to the eyes of him with whom I have to do. He has seen all my past life—my faults, my follies, and my crimes. When I thought myself in darkness and privacy, God's eye was upon me there. In the turmoil of business, God's eye was upon me. In the crowd of my ungodly companions, God's eye was upon me. In the darkness and solitude of night, God's eye was upon me. And God's eye is on me now, and will follow me from this house, and will watch me and observe all my actions, on—on—on—while God lives, and wheresoever God's creation extends.

"O God, Thou has searched and known me;

Thou knowest my down sitting and mine uprising;

Thou understandest my thoughts afar off.

Thou compassest my path and my lying down,

And art acquainted with all my ways

For there is not a word in my tongue,

But, lo! O Lord, Thou knowest it altogether.

Thou hast beset me behind and before, and laid thine hand upon me.

Such knowledge is too wonderful for me!

It is high, I can not attain unto it;

Whither shall I go from thy Spirit?

And whither shall I flee from thy presence?

If I ascend up into heaven, Thou art there,

If I make my bed in hell, behold, Thou art there!

If I take the wings of the morning,

And dwell in the uttermost parts of the sea,

Even there shall thy hand lead me,

And thy right hand shall hold me.

If I say, 'Surely the darkness shall cover me,'

Even the night shall be light about me;

Yea the darkness hideth not from thee,

But the night shineth as the day,

The darkness and the light are both alike to Thee."

FOOTNOTES:

[1] Reid's Chemistry, II. § 37.

[2] Johnson's Turner's Chemistry, § 341.

[3] It might be supposed that such a theory is too palpably absurd to be believed by any save the inmates of a lunatic asylum, had not the writer, and hundreds of the citizens of Cincinnati, seen a lecturer perform the ordinary experiment of producing colored precipitates by mixing colorless solutions, as a demonstration of the self-acting powers of matter. Common sense, being a gift of God, is righteously withdrawn from those who deny him.

[4] John Bull.