THE FIVE GATEWAYS OF KNOWLEDGE
These gateways—which we otherwise name the Organs of the Senses, and call in our mother speech, the Eye, the Ear, the Nose, the Mouth, and the Skin—are instruments by which we see, and hear, and smell, and taste, and touch: at once loopholes through which the soul gazes out upon the world, and the world gazes in upon the soul.
THE EAR: THE MARVELOUS ORGAN OF HEARING
The ear is divided into three parts:
(1) The external ear, made up of the outer portion and passage-way which leads up to the drum.
(2) The middle ear or drum, the continuation of the ear passage internal to the drum membrane, and
(3) The internal ear containing the labyrinth and the nerve of hearing.
DESCRIPTION OF THE
EXTERNAL EAR
The outermost part, the skin-covered auricle, contains no bone, being simply a mass of cartilage covered by skin. It acts as a sound catcher and improves the hearing by directing sound-waves into the opening or external meatus. This meatus or passage-way runs directly inward for an inch and a half. The inner half of the passage-way runs through solid bone, ending abruptly at the membrane or sounding-board of the ear.
THE JOURNEY OF SOUND WAVES TO THE BRAIN
This diagram shows the marvelous structure of the ear, and how sound reaches the brain. There is marked similarity between the ear and a telephone receiver by which we are able to receive messages from the outside world. Hearing is simply the result of sound-waves striking the drum of the ear which set in vibration the bones of the middle ear, and they in turn vibrate the drum of the inner ear. This sets in motion a fluid, and the wave motions are conveyed along the spiral staircase to the wires, or nerves of hearing, and from there to the telephone exchange, or brain.
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DESCRIPTION OF THE
MIDDLE EAR
This part begins at the inner surface of the membrane, and extends inward for about a quarter of an inch. The outer surface of the membrane can be seen by the observer on pulling the top of the auricle or fleshy part of the ear a little upward, so as to straighten out the somewhat curved passageway or meatus. The membrane which is placed transversely across the meatus is whitish-pink or yellowish color.
WHAT THE MIDDLE EAR
CONTAINS
The chief contents of the cavity of the middle ear are three tiny bones called the malleus or hammer bone, the incus or anvil bone, and the stapes or stirrup bone. In addition, an important nerve called the chorda tympani passes across the middle ear chamber. The three little bones contained in the middle ear may be looked upon as the connecting link between the outer ear, which gathers the sounds, and the internal ear, which transmits the effect of the sound waves to the brain, where they are translated into what we call hearing.
From without inward the three little bones lie touching each other, end to end, the outer end of the first bone being implanted between the layers of the drum membrane and the inner end of the innermost bone, fitting into a tiny opening which connects the middle ear with the internal ear. As the result of their lying touching each other, any movement of the ear drum caused by a sound wave striking against its outer aspect, moves the malleus bone; this, in turn, moves the middle incus, and this passes the movement on to the innermost part of the stirrup. This, in turn, passes the movement onward to the fluid or perilymph in the outermost part of the internal ear, and here the endings of the nerve of hearing receive the stimuli which we recognize as “sounds.” (See [Plates].)
THE TWO IMPORTANT TUBES OF
THE MIDDLE EAR
In addition to these contents of the middle ear there are also two tiny openings which, very necessary for health, are nevertheless sometimes a pathway by which serious disease may attack the ear and destroy the hearing. The first is a small passage-way leading from the upper part of the middle ear cavity through the bone to the mastoid antrum, a hollow space in the prominent mass of bone to be felt immediately behind the ear projecting outward and downward from the skull.
The second passage-way opening into the middle ear cavity is that of the Eustachian tube which leads directly to the back of the throat. The importance of this tube is that through it air can find its way directly into the middle ear, so that the air pressure on the two sides of the drum is always kept the same. If it were not for some such arrangement the pressure on the outer side of the drum would become greater than that on its inner surface. This would, of course, push the drum inward, and greatly reduce its mobility.
EXPLANATION OF THE
INTERNAL EAR
This is a complicated structure of bony passages curled on themselves, roughly as in a snail shell, and lined with a delicate membrane. This membrane is, so to speak, floating in fluid. The layer of fluid between it and the bone is called the perilymph, while the two layers of the membrane enclose a similar fluid termed the endolymph. The internal ear or membranous labyrinth may be divided roughly into three chief parts: (1) the cochlea, the true organ of hearing; (2) the semi-circular canals, which control the act of balancing; and (3) the vestibule, or introductory chamber to the semi-circular canals.
The cochlea is a collection of three tubes curled up on themselves in snail-shell fashion.
The central canal of these three is the connecting link by which the sound waves, passed along over the three tiny bones—the malleus, incus, and stapes—finally reach the endings of the main nerve of hearing, the auditory nerve. (See [Plate].)
THE EYE AND ITS WONDERFUL STRUCTURE
The human eye is a hollow globe containing fluids and the crystalline lens. Surrounded by its muscles it lies embedded in a cushion of fat in a conical bony hollow called the orbit. Through an opening in the bones making up the back of the orbit, the optic nerve leads from the back of the eye to the brain.
THE EYELIDS AND
EYE-LASHES
The eyelids are made of layers of muscle and cartilage with an outer surface of skin and an inner surface which is a continuation of the conjunctiva that covers the eyeball. In the edge of the eyelid a series of tiny glands are embedded. The mouths of these open on the margin of the lids. The eye-lashes, whose duty it is to act as a screen, preventing foreign bodies such as dust or other air-born objects getting into the eye, are also inserted in the edge of the lid.
WHAT MAKES THE
TEARS FLOW
About one-eighth of an inch from the internal angle of the eye, a small projection is to be seen on the margin of the lid. In the center of this is a tiny opening through which the tears as they collect in the eye are led away through two small canals to the lachrymal sac in the upper part of the nose. The lachrymal gland, which secretes the tears, or water, of the eye, is situated above on the outer side of the eyeball, between it and the bones of the orbit. The lachrymal gland is constantly secreting tears, which are carried by narrow ducts to the upper surface of the eyeball, whence they flow down over the eye, finally being collected at the inner corner of the eye and passing into the nose through the lachrymal punctures described above. Under certain circumstances, as from emotion, a blow, or the irritation of a cold wind, the tear fluid is secreted faster than it can escape through the punctures, and so flows over the lids and down the cheeks.
HOW THE EYE IS HELD
IN PLACE
The eye is held in its socket or orbit by (1) the optic nerve, (2) by its six muscles attached to various points of its circumference, (3) by the conjunctiva, which is reflected off from its attachments to the outer coat of the eye directly on to the lids, and (4) by the eyelids themselves. (See [Color Plate].)
HOW THE EYE IS
CONSTRUCTED
The cornea is the transparent, bulging, central portion of the eye covering the pupil and the colored iris. Made of tiny transparent cells closely packed together, the cornea is not nourished by blood carried to it by the blood-vessels but by lymph which permeates through it in the tiny channels between the cells. By its curved surface it plays a part in focusing rays of light on to the lens situated just behind the iris.
PICTURE DIAGRAMS SHOWING THE DELICATE STRUCTURE OF THE EYE AND EAR
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Directly behind the cornea come the iris and pupil. The latter is nothing more than a hole in the center of the iris through which light enters the eye.
HOW THE LIGHT IS
REGULATED
The iris is the screen of the eye. Just as the photographer uses a screen with a large opening when he wants more light to enter his camera and a small opening when he requires less, so Nature arranges that the iris automatically contracts or dilates to make a larger or smaller pupil opening, according to the amount of light needed within the eye for purposes of vision. When the light is very bright less is needed in the eye. Thus in brilliant artificial light at night one’s pupil is small. On the other hand, when the light is waning, as in the dusk or semi-darkness, the pupil is enlarged by the iris contracting down to a narrow ring under the outer circumference of the cornea.
WHAT DETERMINES THE
COLOR OF THE EYE
The color of the eye depends on the position and amount of pigment cells in the iris. In the dark brown eye there is an abundance of pigment scattered through the substance of the iris as well as in the front layers nearest the surface. In the blue eye the pigment cells are buried deep in the iris and are fairly plentiful in amount. The colorless eye of the albino is the result of a deficiency of pigment in the iris.
The iris is fixed at its outer circumference, but its inner rim, which makes the border line of the pupil, is free, so that when the iris contracts the pupil becomes larger, since its inner free margin is drawn outwards toward the fixed outer margin. Close up against the deeper surface of the iris comes the crystalline lens.
WHY AND HOW
WE SEE
The lens is a compact body of transparent cells, concave in form, and closely similar to the glass lens of a camera. The lens of the eye, however, differs from the camera’s glass lens because it changes its shape in focusing for objects at different distances. This focusing, which takes place automatically, is known as “accommodation.”
The object of the change in the shape of the lens is that no matter at what angle the rays of light reflected from the object looked at fall on the outer surface of the lens (through the opening in the iris), they may be accurately focused on the surface of the retina, or lining membrane at the back of the eye. When looking at a distant object the lens is fairly flat, because when in this position the rays of light will be accurately focused on the retina. If the eye is now turned to an object near at hand the rays of light from the object are more divergent than in the previous case, and if the lens retained its previous shape they would fail to be focused accurately on the surface of the retina. Hence Nature has arranged that the lens of the eye is elastic, automatically becoming flatter by the action of the ciliary muscle when distant objects are looked at and rounder or deeper when nearer objects are looked at.
EFFECT OF AGE UPON
THE LENS
Up till middle age the eye retains in full this power of automatic accommodation. From middle age onward, however, the lens becomes less and less elastic. As a result the lens constantly remains more or less flattened. Although vision for objects at some distant from the eyes remains perfect, oldish people very frequently have to wear glasses (to correct the too great flatness of the natural lens) to obtain clear vision of objects close at hand.
WHAT HOLDS AND SURROUNDS
THE LENS
The lens is slung in a ligament that is a part of the “ciliary body,” which is a continuation of the choroid coat of the eyeball. This ciliary body is a ring of tissue lying behind the iris connected with the anterior portion of the choroid coat of the eye.
Between the iris and the underlying lens on the one hand and the inner surface of the bulging cornea on the other is a small space or cavity filled with a clear transparent fluid called the aqueous humor.
THE COATS OF
THE EYE
Looking at the white of the eye, the first coat is the transparent conjunctiva, which is reflected back on to the eyeball from the eyelids. Next comes the sclerotic coat, formed of dense whitish tissue, which seen through the transparent conjunctiva makes up the “white of the eye.” The sclerotic coat covers the whole globe of the eyeball with the exception of the transparent bulging cornea in front (which, however, is practically a continuation of the sclerotic), and the back of the eye where the optic nerve enters. The sclerotic is the thickest and densest coat of the eye.
Within the sclerotic coat, and so to speak lining it, comes the choroid coat. Countless blood vessels run through this coat, supplying both the one above it and that beneath it. As this coat approaches the front of the eye under the circumference of the cornea, it thickens into the ciliary body, forming a dense ring of tissues underneath the junction of the cornea and the sclerotic coat.
THE WORK OF THE
RETINA
The innermost coat of the eye is called the retina. This coat contains the nerve endings of the optic nerve which, coming through the opening in the bony orbit, passes through the sclerotic and choroid coats. After entering the eye, the optic nerve divides into myriads of fibers, which, spreading from the point of entrance at the back of the eye, form a fibrous network all over its inner surface. In addition to this network of nerve fibers and highly specialized nerve cells, tiny blood vessels entering with the optic nerve branch out on all sides over the retina.
THE RODS AND
CONES
The retina is a comparatively thick membrane composed of eight layers of different kinds of nervous tissue. The essential layer, that of the “rods and cones,” is the seventh from within outward. Thus a ray of light on entering the eye must pass through six superficial layers before it reaches the “rods and cones.”
The “rods and cones” are lying on a layer of colored or pigment cells whose duty it is to prevent diffusion of light within the eye. The eyeball, therefore, is to all intents a camera obscura, the iris representing the shutter, the crystalline lens the camera lens, and the layer of “rods and cones” the sensitive plate. When a ray of light falls on the layer of the “rods and cones,” this layer receives a nervous stimulus which is conveyed by the optic nerve to the brain. It is these sensations which the brain translates into what we term sight.
Where the optic nerve enters the back of the eye, there are no “rods and cones,” hence rays of light falling on this portion of the retina send no stimulus to the brain; in other words, images falling on the “blind spot” are not visible.
The “yellow spot” is a small area at the center at the back of the eye where the retina is very thin, consisting of little more than a single layer of “cones.” Images which fall upon this region are seen with the greatest distinctness.
HOW THE SENSE OF SIGHT
IS PRODUCED
Sight is a nervous sensation due to the translation by the brain of the effects caused by rays of light being reflected from some object in front of the eye on to the innermost layer of the eye, the retina.
When an object is looked at, rays of light which reach the object from some source of light (such as the sun, a lamp, etc.) fall on the transparent outer part of the eye, the cornea. On account of its curved surface these rays of light are more or less bent inward so as to fall more or less perpendicularly on the forward anterior convex surface of the lens. If the light is weak or dim, the iris, which lies in front of the lens, will automatically contract down so as to make the opening by which the rays can enter the posterior chamber of the eye (the part behind the lens) as large as possible.
If the light is very bright the muscle fibers in the iris will relax so that the iris itself gets larger, and its central opening smaller, so that too much light may not enter. Passing through the lens the rays are focused by the lens so that they are brought together to a point exactly on the surface of the retina.
Here their presence has a certain effect on the rod and cone layer of the retina, the result of which is conducted along the optic nerve to the brain, where it is transformed into what we know as sight.
HOW WE ARE ABLE TO TASTE, SMELL AND FEEL
HOW THE NERVES RUN INTO THE SPINAL CORD ON THE WAY TO THE BRAIN
The lower drawing shows how the spinal cord rests in the backbone, and how the nerves pass in and out, those of sensation passing into the spinal cord, as shown in the magnified section above.
THE AREAS OF THE TONGUE IN WHICH THE CELLS OF TASTE ARE DISTRIBUTED
The tongue is covered with various types of taste-bulbs, most of the distinct types that appreciate the sweet, the acid, and the bitter being found in the areas marked on the diagram.
THE OUTER SIDE OF THE NOSE, SHOWING THE NERVES OF SMELL AND FEELING
THE INNER PART OF THE NOSE, SHOWING THE FIBRES FROM THE OLFACTORY BULB
THE NOSE: ORGAN OF SMELL
The nose is composed partly of bone and partly of cartilage, the cartilages being firmly attached to the bones and to one another by fibrous tissue.
The bridge consists of the two nasal bones which are projections of the frontal bone of the forehead. From these are continued the nasal cartilages which form one-half to two-thirds of the external nose.
The interior is a large and complicated chamber divided into the right and left nares, or nostrils, by the partition called the septum. This, like the external part, consists of cartilage in front, attached to bone at the back.
The Nostrils, opening on the face in front, run backward for about two inches and open into the pharynx behind. But the single canal is divided into three separate passages some distance inward. This division is effected by the turbinated bones which jut out into the nostril and thus form the upper, middle, and lower air-channels. In this way the warm surface with which cold inhaled air comes in contact is greatly enlarged.
From the mouth cavity the nose is separated by the hard palate. On the external nose, scattered near the tip, are numerous hairs, sebaceous glands, and sweat glands. These glands are very liable to get blocked, giving rise to inflamed spots, and when hairs are pulled out small abscesses are apt to form.
Membrane.—The whole of the interior surface is lined with mucous membrane, and as this has a large area, and is very well supplied with blood, it raises the temperature of inspired air. The mucous membrane of the nose is continuous with that of the pharynx. Any inflammation, such as that which constitutes a “cold in the head,” is therefore extremely liable to extend backward and finally reach the bronchial tubes and lungs.
Over this membrane spread a multitude of small threads or nerves resembling the twigs of a branch; there are many such branches within the nostril, and they join together so as to form larger branches, which may be compared to the boughs of a tree. These finally terminate in a number of stems, or trunks, several for each nostril, which pass upward through apertures provided for them in the roof of the arched cavity, and terminate in the brain.
We have thus, as it were, a leafless nerve-tree whose roots are in the brain, and whose boughs, branches, and twigs spread over the lining membrane of the nostril. This nerve is termed the Olfactory.
When we wish to smell anything—for example, a flower—we close our lips and draw in our breath, and the air which is thus made to enter the nose carries with it the odorous matter, and brings it in contact with the ramifications of the nerve of smell. Every inspiration of air, whether the mouth is closed or not, causes any odorous substance present in that air to touch the expanded filaments of the nerve.
In virtue of this contact or touching of the nerve and the volatile scent, the mind becomes conscious of odor, though how it does so we know as little as how the mind sees or hears; we are quite certain, however, that if the olfactory nerve be destroyed, the sense of smell is lost.
Besides its endowment by the olfactory nerve, or nerve proper of smell, the nostril, especially at its lower part, is covered by branches of another nerve (known to anatomists as the fifth), of the same nature as those which are found endowing every part of the body with the susceptibility of heat, cold, smoothness, roughness, pleasure, and pain. It is on this nerve that pungent vapors, such as those of smelling-salts, strong vinegar, mustard, and the like, make the sharp impression with which all are familiar.
Can the Sense of Smell be Educated?—The extent to which the sense of smell may be educated far exceeds what most imagine can be realized from this sense. There are probably as many odors as there are colors or sounds; and the compass of one nostril in reference to the first, likely differs as widely from that of another, as the compass of the eye or the ear does in reference to the last two. The wine merchant, the distiller of perfumes, the manufacturer of drugs, the grower of scented plants, the epicure in things savory, the tobacco dealer, and many others, have by long training educated themselves to distinguish differences of odor which escape an uneducated and unpracticed nostril, however acute by natural endowment.
Perfumes.—Much importance attaches to the use of perfumes by both ancient and modern civilized nations. But all the ancient nations who had attained to civilization, were addicted to the use of perfumes to an extent to which no modern people at the present day affords any parallel. Not merely as contributing to the luxury of the body were perfumes so prized. They were used at every sacred ceremonial; lavishly expended at the public religious services; and largely employed at the solemn rites which were celebrated at the burial of the dead.
THE TONGUE: THE ORGAN OF TASTE
The organ of taste is generally held to be synonymous with the tongue, but, in reality, the throat and the nostril are as much concerned as the tongue in the perception of taste. The power of these portions of the body to distinguish savors mainly depends, as in the case of the eye and the ear, upon their connection with the brain through those fine white nerves which have been already referred to. The tongue and the auxiliary organs of taste are largely supplied with nerves, and through them those sensations are experienced which we connect with the words taste, savor, sapidity; sweet, salt, sour, bitter, and the like.
Membrane of the Tongue.—At certain points the membrane of the tongue forms distinct folds, containing fibrous or muscular tissue, which act to a certain extent as ligaments to the tongue. The most considerable of these folds is termed the frœnum (or bridle) of the tongue, and connects its anterior free extremity with the lower jaw. Other folds of mucous membrane pass from the base of the tongue to the epiglottis; while from the sides of the base, passing to the soft palate, are seen two folds on either side, the “pillars of the fauces.”
The upper surface of the tongue is divided into two parts by a long furrow, commencing at the tip, and extending back about two-thirds of the tongue’s length.
Muscles of the Tongue.—The muscles of the tongue are usually divided into two groups—viz.: the extrinsic muscles, which attach the tongue to certain fixed points external to it, and move it on them; and the intrinsic muscles, which pass from one part of the tongue to another, constitute its chief bulk, and move it on itself. These intrinsic muscular fibers run vertically, transversely, and longitudinally, and are so interlaced as mutually to support one another, and to act with the greatest advantage.
The Bulbs of Taste.—The mucous membrane is invested by stratified cells, which, over the surface of the tongue, cover little vascular projections termed, papillæ. At the back of the tongue are some eight or ten papillæ of quite a different nature, called “circumvallate.” They are arranged to form a V with its angle pointing backward. In the epithelium lining the trenches between the papillæ, curious little bodies called taste-bulbs are lodged. Each taste-bulb looks like a flask-shaped barrel or box, the walls of which are composed of flat elongated cells fitted side by side like the staves of a cask. The taste-bulbs open each by a little pore into the trench, and into the deeper part a nerve enters. The impressions are carried by the nerve directly to the brain in either the fifth or the ninth cranial nerves.
Before the substance can stimulate the terminals it is necessary for its aromatic principles to be in solution. This is generally effected through the agency of the saliva.
Four distinct gustatory qualities are appreciated by the sense of taste—sweetness, bitterness, acidity, and salinity. The intensity of the sensation of taste varies with (1) the area of the surface stimulated, (2) the concentration of the stimulant, (3) the length of the period of application, and (4) the temperature of the substance tasted. Tractile impressions, such as harshness, coolness, and astringency, are erroneously attributed to taste.
Mis-Educated and Educated Taste.—Of all the organs of the senses, that of taste is probably the one which receives the worst usage at our hands. The eye, the ear, and the nose are not educated at all, or their education is left to chance, but the tongue is deliberately mis-educated, perverted, and led astray. We eat what we should not eat; drink what we should not drink: eat too much of what we may eat, and drink too much of what we may drink. And the result is, that we ruin our health, enfeeble our bodies, dull our intellects, brutalize our feelings, and harden our hearts.
Yet assuredly taste has its legitimate domain, and it is as unworthy of man’s true dignity that he should be content to live upon the husks that the swine do eat, as that he should be miserable if he do not fare sumptuously every day. All the other senses have a direct interest in the practical decisions of the sense of taste. Drunkenness and dyspepsia dim the eye, dull the ear, blunt the nostril, and make the hand tremble.
A Victim to the Other Senses.—The sense of taste, in truth, is at the mercy of the other senses; and though it can revenge itself for their neglect or misuse of it, it is a sufferer by its own revenge.
Helpless, selfish, and exacting, the dependent of the other senses, and the servant of the body rather than of the soul, it frequently links us more with the lower animals than with higher existences, and has no element of ethereality about it.
A feast, indeed, may furnish pleasure to every sense, but it is usually not till hunger is appeased that the higher senses are ministered to. But the tongue, as the organ of taste, is the commissary-general, without whose supplies the other senses can achieve no conquests, and it is entitled to its share in the honors assigned to the united five; but its own sword is seldom drawn, and its aspect is not heroic.
THE HAND: CHIEF ORGAN OF TOUCH
The last of the bodily senses is Touch. It has the widest gateway, and largest apparatus of them all; for though we are in the habit of speaking of it as localized in the fingers, it reigns throughout the body, and is the token of life in every part. The nearest approach to death which can occur in a living body, is the condition of paralysis or palsy, a death in life, marked in one of its forms by the loss of that sense of touch which is so marked an endowment of every active, healthy creature.
The tactile susceptibilities of the skin depend, as do the peculiar endowment of the other organs of the senses, on its plentiful supply with those wondrous living nerves, which place in vital communication with each other all the organs of the body, on the one hand; and that, mysterious living center, the brain (and its adjuncts), on the other.
Our simplest conception of an organ of sense is supplied by the finger, which whether it touches or is touched, equally realizes that contact has been made with it, and enables the mind to draw conclusions regarding the qualities of the bodies which impress it. Now, after all, every one of the organs of the senses is but a clothed living nerve conscious of touch, and they differ from each other only in reference to the kind of touch which they can exercise or feel. Keeping in view that to touch and to be touched is in reality the same thing, so far as the impression of a foreign body is concerned, we can justly affirm that the tongue is but a kind of finger, which touches and is touched by savors; that the nostril is touched by odors; the ear by sounds; and the eye by light.
The Hand is emphatically the organ of touch, not merely because the tips of the fingers, besides being richly endowed with those nerves which confer sensitiveness upon the skin of the whole body, possess in addition an unusual supply of certain minute auxiliary bodies, called “tactile corpuscles,” but because the arrangement of the thumb and fingers, and the motions of the wrist, elbow, and arm, give the hand a power of accommodating itself spontaneously to surfaces, which no other part of the body possesses. Moreover, when we speak of the hand as the organ of touch, we do not refer merely to the sensitiveness of the skin of the fingers, but also to that consciousness of pressure upon them in different directions, by means of which we largely judge of form.
When a blind man, for example, plays a musical instrument he is guided in placing his fingers, not merely by the impression made upon the skin of them, but also by impressions conveyed through the skin to these little bundles of flesh called muscles, which move the fingers.
In many respects the organ of touch, as embodied in the hand, is the most wonderful of the senses. The organs of the other senses are passive, the organ of touch alone is active. The eye, the ear, and the nostril stand simply open: light, sound, and fragrance enter, and we are compelled to see, to hear and to smell; but the hand selects what it shall touch, and touches what it pleases. It puts away from it the things which it hates, and beckons toward it the things which it desires; unlike the eye, which must often gaze transfixed at horrible sights from which it cannot turn; and the ear, which cannot escape from the torture of discordant sounds; and the nostril, which cannot protect itself from hateful odors.
Moreover, the hand cares not only for its own wants, but, when the other organs of the senses are rendered useless, takes their duties upon it. The hand of the blind man goes with him as an eye through the streets, and safely threads for him all the devious ways; it looks for him at the faces of his friends, and tells him whose kindly features are gazing on him; it peruses books for him, and quickens the long hours by its silent readings.
It ministers as willingly to the deaf; and when the tongue is dumb and the ear stopped, its fingers speak eloquently to the eye, and enable it to discharge the unwonted office of a listener.
The organs of all the other senses, also, even in their greatest perfection, are beholden to the hand for the enhancement and the exaltation of their powers.
It constructs for the eye a copy of itself, and thus gives it a telescope with which to range among the stars; and by another copy on a slightly different plan, furnishes it with a microscope, and introduces it into a new world of wonders.
It constructs for the ear the instruments by which it is educated, and sounds them in its hearing till its powers are trained to the full.
It plucks for the nostril the flower which it longs to smell, and distills for it the fragrance which it covets.
As for the tongue, if it had not the hand to serve it, it might abdicate its throne as the “Lord of Taste.” In short, the organ of touch is the minister of its sister senses, and, without any play of words, is the handmaid of them all.
And if the hand thus munificently serves the body, not less amply does it give expression to the genius and the wit, the courage and the affection, the will and the power of man. Put a sword into it, and it will fight for him; put a plow into it, and it will till for him; put a harp into it, and it will play for him; put a pencil into it, and it will paint for him; put a pen into it, and it will speak for him, plead for him, pray for him.
What will it not do? What has it not done? A steam engine is but a larger hand, made to extend its powers by the little hand of man! An electric telegraph is but a long pen for that little hand to write with! All our huge cannon and other weapons of war, with which we so effectually slay our brethern, are only Cain’s hand made bigger, and stronger, and bloodier!
What, moreover, is a ship, a railway, a lighthouse, or a palace—what, indeed, is a whole city, a whole continent of cities, all the cities of the globe, nay, the very globe itself, in so far as man has changed it, but the work of that giant hand, with which the human race, acting as one mighty man, has executed its will!
What an instrument for good it is! What an instrument for evil! and all the day long it never is idle. There is no implement which it cannot wield, and it should never in working hours be without one. It is the one universal craftsman. For the queen’s hand there is the scepter, and for the soldier’s hand the sword; for the carpenter’s hand the saw, and for the smith’s hand the hammer; for the farmer’s hand the plow; for the miner’s hand the pick; for the sailor’s hand the oar; for the painter’s hand the brush; for the sculptor’s hand the chisel; for the poet’s hand the pen; and for the woman’s hand the needle.
For each willing man and woman there is a tool they may learn to handle; for all there is the command, “Whatsoever thy hand findeth to do, do it with all thy might.”
Such are the five entrance-ways of knowledge, which John Bunyan quaintly styles Eye-gate, Ear-gate, Nose-gate, Mouth-gate, and Feel-gate.