The Senses and the Mind

by Anonymous

The eye assists us greatly, indeed almost exclusively, in determining the motions of bodies; yet in this we require experience, and after all we are frequently deceived. When a body moves in a straight line from us, we cannot tell whether it moves or not, and then only come to the conclusion that it recedes in consequence of its becoming more obscure, and from a change in its relative position to other objects which we know to be stationary. When we travel in a railway carriage, the banks, the hedge-rows, and the fields, seem as if gliding with extreme velocity away from us. It is only by a course of reasoning that we know such is not the fact; it is true that the course of reasoning is very short and simple, yet still that reasoning is requisite; indeed, it has been acknowledged only in modern times that the sun is stationary, and that the world moves. Bodies moving with extreme velocity produce a continuous impression on the eye; thus, for example, if a stick burning at one end be rapidly whirled, the burning end produces the appearance of a fiery circle. The spokes of a coach-wheel, rolling round very rapidly, present the appearance of an indistinct expansion. On the contrary, bodies moving with extreme slowness appear to casual observation as stationary; thus the act of growing, in ordinary plants and animals, is not appreciated, though the result is demonstrated in due time.

The eye, moreover, may be deceived by artificial representations, as by painting (take the Diorama as an example) or by models. We have seen flowers so truthfully modelled in wax that, by the eye alone, no distinction between them and natural flowers could have been detected.

The same observations apply to magnitude and distance. Objects of gigantic magnitude, as, for instance, the pyramids of Egypt, at first appear less than they are in reality; and it is only by admeasurement, examination, and comparison, that the mind becomes impressed with the idea of their immensity. A building, the details of which are in just harmony, always appears to be smaller than it is, because no discordance betrays the vast preponderance of certain parts over the littleness of others. Habit, or, in other words, education, is essentially requisite to aid the eye in its appreciation of magnitude.

We may say the same with respect to distance. An infant does not distinguish between near and distant objects; its eyes have yet to become educated, and so have those of adults placed in circumstances to which they are unaccustomed. For example, the walls of a city, reared in a vast level plain, and descried at a distance, appear to be far nearer than the traveller will find them to be; again, when standing on the beach, we look at a ship in the distance, we are apt to think it closer to the shore than we should prove it to be were we to traverse the distance in a boat. A sailor would judge of the distance accurately.

How much the accuracy and utility of the eye depend upon practice or education may be illustrated by the case of a boy, who, as described by Cheselden, was born quite blind, but was suddenly restored to sight, at the age of twelve, by the skilful removal of the cataract. At first, he was impressed with the idea that all the objects which he saw around him touched his eyes, in the same manner as in the act of touch they came in contact with the skin. He could neither estimate distance, nor distinguish one object from another, until he had applied the test of touch as a corrective and assistant.

It may here be asked, how the fact is to be explained that, though images are pictured on the retina inverted, we do not see them as such, but in their true position? When we say that the eye sees, we use popular, but not strictly correct language; the eyes are the organs or instruments of vision—that is, for transmitting certain qualities of matter to the mind; it is not the image on the retina which the mind contemplates, for we are utterly unconscious that such an image exists—it is the object itself. "To expect that the impression from an inverted image on the retina should produce the perception of a similar position in the object viewed, is to commit the error of mistaking these images for the real objects of perception, whereas they are only the means which suggest the true perceptions. It is not the eye which sees; it is the mind." "The analogy which the optical part of the eye bears to a camera obscura has perhaps contributed to the fallacy in question; for in using that instrument we really contemplate the image which is received on the paper, and reflected from it to our eyes; but in our own vision nothing of this kind takes place."

We scarcely know whether we can place among optical illusions those strange apparitions of departed persons, of friends at a distance, or of singular and grotesque faces or figures, of which we have many authentic narratives. These we take to be strong impressions on the mind alone, (for no image can there be on the retina,) the result of some morbid condition of the brain and nervous system. Such was the evil genius which Brutus saw in his tent before the battle of Philippi, and such the air-drawn dagger of Macbeth—such also were the phantoms seen by Nicolai, the philosophic bookseller of Berlin, who has given an admirable account of his mental visions, referring them to their true source, at the very time that the illusions visited him. In some states of body, we see grotesque and ludicrous objects, while our eyes are shut, and, as we can testify, often not before we have shut our eyes, and thereby closed the door of access through those organs to the mind. What horrible phantasms terrify the unhappy sleeper labouring under night-mare! What strange things does the delirious sufferer mentally behold, and through what strange scenes, real to him, does he pass! We see, we converse, we laugh, we mourn, we feel pleasure and anguish, even in our dreams. These, then, are not optical but mental illusions—no figure is made upon the retina appealing to the mind, but the mind itself sees things which are not, and is delighted or terrified by its own involuntary creations.[12]

[12] See "An Essay towards a Theory of Apparitions," by John Ferriar, M.D., 1813; and "Sketches of the Philosophy of Apparitions; or, An Attempt to trace such Illusions to their Physical Causes," by Samuel Hibbert, M.D., 1824.

In former times, craft, under the name of religion, availed herself of these mental illusions, and extorted gifts of lands and gold from the terrified, perhaps most guilty sufferer, in order that his peace with the church (so miscalled) might be made, and masses said for the repose of his soul. He was taught to buy his entrance into heaven—not with the Pearl of great price—not by presenting before the Judge of all mankind the merits and the atonement of the Messiah, but by founding a monastery, or by adding to its treasures and domains. His faith was placed, not on the promises of God in Christ, but on the promises of a mere mortal at best—yes, a mortal, who knew that while he promised he was weak as other men; In concluding our observations upon the sense of sight, we may refer to a few striking passages in Scripture, of great force, and well calculated to excite reflection. "He that formed the eye, shall he not see?"[13] No secrets are hidden from God; no, not the secrets of the heart, for these are written on a tablet which he, and he alone, can read. May our prayer be, "Let the meditation of my heart be acceptable in thy sight, O Lord, my strength, and my Redeemer!"[14] "Enter not into judgment with thy servant: for in thy sight shall no man living be justified."[15] In the sight of God, we speak figuratively, all men are sinners, and as sinners condemned; but God will not enter into judgment with those who, by faith in the atonement, looking to the Saviour, as the Israelites looked to the brazen serpent in the wilderness, turn away from their wickedness, and become examples "of the believers, in word, in conversation, in faith, in purity."