Chapter LI: 1009. Why do we perspire?

Because the skin is filled with very _minute pores_, which act as outlets for a portion of the water of the blood, that serves to _moisten and cool_ the surface of the body, and to carry away some of the matter _no longer needed in the system_.

1010. _How is the perspiration formed?_

By very small _glands_, which lie embedded in the skin. It is estimated that there are about 2,700,000 perspiratory glands distributed over the surface of the body, and that these glands find outlets for their secretion through no less than _seven millions of pores_.

1011. _What is insensible perspiration?_

Insensible perspiration is that _transmission of watery particles through the skin_ which is constantly going on, but which takes place so gently that it cannot be perceived. It is, however, very important in its results, as no less than _from twenty to thirty-three ounces of water may pass imperceptibly through the skin in twenty-four hours_.

1012. _What is sensible perspiration?_

Sensible perspiration is that moisture which exudes upon the skin _in drops large enough to be perceptible_, when the body is heated by exercise or other means.

[Verse: "And Elisha sent a message unto him, saying, Go and wash in Jordan seven times, and thy flesh shall come again to thee, and thou shalt be clean."--II KINGS V.]

1013. _Why does a sudden change from heat to cold bring on illness?_

Because the effect of cold _arrests the action of the vessels of the skin_, and suddenly throws upon the internal organs the excretory labour which the skin should have sustained.

1014. _Why does a chill upon the skin frequently produce inflammation of the lungs?_

Because the lungs and the skin together discharge the chief proportion of the watery fluid of the body. _When the skin's action is checked, the lungs have to throw off a much greater amount of fluid._ The lungs, therefore, become _over worked_, and inflammatory action sets in.

1015. _Why does cleanliness promote health?_

Because every atom of dirt which lodges upon the surface of the body serves to clog and check the working of those _minute pores_, by which much of the fluid of the body is changed and purified.

In the internal parts of the system, the Creator has made ample provision for cleanliness. Every organ is so constituted that it cleanses and lubricates itself. Every surface of the inner body is perfectly clean, and as soft as silk.

Nature leaves to man the care of those surfaces which are under his immediate observation and controul; and he who, from idleness, or indifference to nature's laws, is guilty of personal neglect, _opposes the evident intentions of the Creator_, and must sooner or later pay the penalty of disobedience.

1016. _Why does exercise promote health?_

Because it _assists all the functions upon which life depend_. It quickens the circulation, and thereby nourishes every part of the body, causing the bones to become firm, and the muscles to become full and healthy. It promotes breathing, by which oxygen is taken into the system, and carbon thrown off, and thereby it produces a higher degree of organic life and strength than would otherwise exist. It promotes perspiration, by which, through the millions of pores of the skin, much of the fluid of the body is changed and purified. And it induces that genial and diffused warmth, which is one of the chief conditions of a high degree of vitality.

[Verse: "Love not sleep lest thou come to poverty: open thine eyes, and thou shalt be satisfied with bread."--PROV. XX.]

1017. _Why do we feel fatigue?_

Because those organs which stimulate the mechanism of the body to act, _themselves require rest and repair_. When the brain and nerves arrive at that state, they make their condition known to the system generally, by indications which we denominate _fatigue_.

1018. _Why, after rest, do we return invigorated to our labours?_

Because the nervous system has accumulated, during the hours of rest, a fresh amount of that _vital force_ which we call the nervous fluid, and by which the various organs of the body are excited to perform the duties assigned to them.

1019. _What is sleep?_

Sleep is understood to be that state of the body in which _the relation of the brain to some parts of the body is temporarily suspended_.

There are some parts of the body that _never sleep_: such are the heart, the lungs, the organs of circulation, and those parts of the nervous system that direct their operations.

But when sleep overtakes the system, it seems as if the _relations_ of those parts under the controul of the will were temporarily suspended; as if, for instance, those nerves which move the arms, the legs, the eyes, the tongue, &c., were all at once unfastened, just as the strings of an instrument are relaxed by the turning of a key, or the throwing down of a bridge over which they were stretched.

What is meant by the temporary suspension of the relation of the
brain to some parts of the body, may be thus explained. Notice
a man when he sits dosing in a chair: at first his head is held
up, the brain controlling the muscles of the neck, and keeping
the head erect. But drowsiness comes on, the brain begins to
withdraw its influence, and the muscles of the neck becoming as
it were "unstrung," the head drops down upon the breast. But the
sleep is unsound, and disturbed by surrounding noises. The brain
is therefore frequently excited to return its influence to the
muscles, and draw up the head of the sleeper. He gives a sudden
start, every muscle is tightened in an instant, up goes the head,
the eyes open, the ears listen, until a feeling of security
and composure returns; the sleep again deepens, _the nervous
connection is again withdrawn_, and then down drops the head as
before.

[Verse: "Yet a little sleep, a little slumber, a little folding of the hands to sleep: So shall thy poverty come as one that travelleth; and thy want as an armed man."--PROVERBS XXV.]

1020. _Why do we dream?_

Dreams appear to arise _from the excitement of the brain during those hours when its connection with the other parts of the living organism is suspended_. For instance: a man dreams that he is pursued by a furious animal, and the mind passes through all the excitement of flying from danger; but the _connection_ between the moving power, and the machinery of motion being suspended, no motion takes place. The same impressions upon the brain, when the nerves were "strung" to the muscles, would have caused a rapid flight, and a vigorous effort to escape from the apprehended danger.

1021. _Why do suppers, when indigestible substances are eaten, produce dreaming?_

Probably because, as the digestive organs are oppressed, and those parts of the nervous system which stimulate the organs of digestion are _excited by excessive action_, those portions of the brain which are not immediately employed by the digestive process are disturbed by that _sympathy_ which is observed to prevail between the relative parts and functions of the body.

1022. _Why do we yawn?_

Because, as we become weary, the nervous impulses which direct the respiratory movements are enfeebled. It has been said that those movements are involuntary, and that the parts engaged in producing them are not subject to fatigue. But the operation of breathing is, _to some extent, voluntary_, though when we cease to direct it voluntarily, it is involuntarily continued by organs which know no fatigue.

When, therefore, we feel weary--still controuling our breathing in our efforts to move or to speak--there frequently arrives a period when, for a few seconds, the respiratory process is suspended. It seems to be the point at which the voluntary nerves of respiration are about to deliver their office over to the involuntary nerves; but the pause in the respiration has caused a momentary deficiency of breath, and the involuntary nerves of respiration, coming suddenly to the aid of the lungs, cause a spasmodic action of the parts involved, and _a yawn_, attended by a _deep inspiration to compensate for the cessation of breathing_, are the result.

[Verse: "And it shall be, when they say unto thee, Wherefore sighed thou that thou shalt answer, For the tidings, because it cometh; and every heart shall melt, and all hands shall be feeble."--EZEKIEL XXI.]

1023. _Why do we cough?_

Because the respiratory organs are excited by the presence of some body foreign or unnatural to them. A cough is an effort on the part of the air tubes to free themselves from some source of irritation. And so important are the organs of breathing to the welfare of the body, that the muscles of the chest, back, and abdomen, _unite in the endeavour to get rid of the exciting substance_.

1024. _Why do we sneeze?_

Because particles of matter enter the nostrils and excite the nerves of feeling and of smell. In sneezing, as in coughing, the effort is to free the parts affected from the intrusion of some matters of an objectionable nature. And in this case, as in the former one, there is a very general sympathy of other organs with the part affected, and an energetic effort to get rid of the evil.

1025. _Why do we sigh?_

The action of sighing arises from very similar causes to those of yawning. But in sighing, the nervous depression is caused by _grief_; while in yawning, it is the result of _fatigue_. In sighing, the effect is generally erased by an _expiration_--in yawning by an _inspiration_. The mind, wearied and weakened by sorrow, omits for a few seconds to continue the respiratory process; and then suddenly there comes an involuntary expiration of the breath, causing a faint sound as it passes the organs of the voice.

1026. _Why do we laugh?_

Laughing is caused by the very opposite influences that produce sighing. The nervous system is highly excited by some external cause. The impression is so intense, and the mind so fixed upon it, that the respiratory process is irregular, and uncontrolled. Persons excited to a fit of laughter generally hold their breath until they can hold it no longer, and then suddenly there is a quick expiration causing eccentric sounds, the mind being too intently fixed upon the cause of excitement, _either to moderate the sounds, or to controul the breathing_.

[Verse: "Except ye utter by the tongue words easy to be understood, how shall it be known what is spoken? for ye shall speak into the air."--CORINTH. XIV.]

1027. _Why do we hiccough?_

Hiccough is caused by a spasmodic twitching of the diaphragm, a thin muscular membrane which divides the chest from the abdomen. It generally arises from sympathy with the stomach; and it is highly probable that the muscular twitches and jerks are so many efforts on the part of the diaphragm to _assist the stomach to get rid of some undigested matter_.

1028. _Why do we snore?_

Snoring is caused by air sweeping through the passages that lead from the mouth through the nostrils, and which, in our waking moments, are capable of certain muscular modifications to adapt them to our breathing. But as in sleeping the nervous controul over them is withdrawn, they are left to the action of the air which, in sweeping by them, _sets them in vibration_.

We have endeavoured, by the employment of the simplest language,
and by reference to some of the most familiar phenomena of nature,
to impart to the reader a clear conception of those sublime laws
which control our being, and afford evidence of the goodness and
power of that Almighty God to whom we are indebted for the life
that we enjoy, and the varied and beautiful existences which, to
the rightly constituted mind, make the earth a vast aggregation of
interesting objects. We will now, before we pass on to the final
section of our work, review some of the more important facts that
have been communicated, and devote a few pages to meditations upon
the formation of the human body--that wonderful temple of which
each of us is a tenant.

We have described man's organisation. What is that organisation
for? _It is to make use of the elements upon which man exists._
The lungs make use of the air; the eye makes use of the light;
the stomach, and the system generally, make use of water; every
part of the body uses heat; and all parts of the system demand
food. The hand feeds as constantly as the mouth. The mouth is the
receptacle of food, by which the body is to be fed; the stomach is
the kitchen in which food is prepared for the use of the body; and
the blood-vessels are the canals through which the food is sent to
those members of the body that are in need of it. When we speak
of man's "organs" or "members," we speak of those parts of the
living machinery by which the elements are used up, or employed,
for man's benefit. And this view of the subject, bearing in mind
that the body is held together as the temple of a living Spirit,
superior to mere flesh and blood, gives us a higher and clearer
perception of the distinction between the body and the soul than
that which we might otherwise entertain. The body is a machine,
working for the spirit, which is its owner. While the machine
works, the spirit directs and influences its actions. But when the
machine stops, the spirit resigns its power over a ruined temple,
quits it, and flies to a region where, as a spirit, it becomes
subject to a new order of existence consistent with its severance
from earthly things and laws, and there it enters upon its eternal
destiny, according to the judgments and appointments of God. It is
no longer dependent upon a relation between spiritual and material
laws.

[Verse: "Not unto us, O Lord, not unto us, but unto thy name give glory, for thy mercy, and for thy truth's sake."--PSALM CXV.]

Suppose that the air which man breathes, instead of returning
from his lungs clear and imperceptible to sight, were tinged with
colour; we should see, that every time a man breathed, the air
would rush in a stream into his mouth, and then return again;
and the air which returned would, being warm, be lighter than
the outer air, and would rise upward over the man's head, where,
cooling and mingling with the outer air, it would descend again.
We do, in fact, see this action evidenced; when in winter time the
cold condenses the vapour of the breath, we see the little cloud
constantly rising before the breather's face, and dispersing in
the surrounding air.

Is it not a wonderful thing that that clear and elastic substance,
which you cannot feel, though it touches every part of your body,
and which you cannot see, is composed of two distinct bodies,
having very different properties; and that the two bodies can
easily be separated from each other?

Air is of the first importance to life. Hence it is provided
for us everywhere. We require air every second, water every few
hours, and food at intervals considerably apart. Air is therefore
provided for us everywhere. Whether we stand or sit; whether we
dwell in a valley or upon a mountain; whether we go into the
cellar under our house, or into the garret at the top of it, air
is there provided for us. God, who made it a law that man should
breathe to live, also sent him air abundantly, that he might
comply with that law. And all that is required from man in this
respect is, that he will not shut out God's bounty, but receive it
freely.

As we have employed the idea that if the air were coloured we
should have the opportunity of marking the process of breathing,
let us enlarge upon this, and suppose that every time the air were
returned from the lungs it became of a darker colour, the darkness
denoting increasing impurity. If we placed a man in a room full
of pure air, we should see the air enter his lungs, and sent back
slightly tinged; but this would disperse itself with the other
air of the room and scarcely be perceptible. As the man continued
to breathe, however, each measure of air returning from the lungs
would serve to pollute that abiding in the room, until at last the
whole mass would become cloudy and discoloured, and we should see
such a change as occurs when water is turned from a pure and clear
state into a muddy condition. The air does become polluted with
each respiration, and although it is colourless, it is as impure
as if with every breath given off from the lungs it became of a
dark colour in proportion to its impurity.

Thus we see how important it is that we should provide ourselves
with pure air; and that, in seeking warmth and comfort in
our houses, we should provide an adequate supply of fresh
atmosphere--because it is more vital to life than either water or
food.

Indeed, so constant is our requirement of air, that _if we had
to fetch it, for purposes of breathing, or simply to raise it
to our mouths, as we do water when we drink, it would be the
sole occupation of our lives_--_we could do nothing else_. For
this reason, God has sent the air to us, and not required us to
go to the air. And the great error of man is, that in too many
instances, he shuts off the supply from himself, and brings on
disease and pain by inhaling a poisonous compound, instead of air
of a healthful kind, which bears an adaptation to the wants of
life.

[Verse: "There is a natural body, and there is a spiritual body."--I CORINTHIANS XV.]

Whilst the rooms of our house are filled with air, it is otherwise
with water, which we require in less degree than air. If we have
not the artificial means by which water is brought to our houses,
through the pipes of a water company, there is a spring or a pump
in the garden; or in the absence of these, a good sound cask,
standing at the end of our house, forming a receptacle to the
water-pipes that surround it, provides us with a supply of water
distilled from the clouds. If we were to drink a good draught of
water once a day, that would be sufficient for all the purposes
of life, as far as regards the alimentary uses of water. Man is,
therefore, allowed to go to the stream for his drink, and is
required to raise it to his lips at those moments when he uses it.

Although, in breathing, man separates the _oxygen_ of the air from
the _nitrogen_ thereof, he does not separate the _oxygen_ of the
water from the _hydrogen_. Water, in fact, undergoes no change
in the body, excepting that of admixture with the substances of
the body. And its uses are, to moisten, to cool, to cleanse, and
also to nourish the parts with which it comes in contact. But it
affords no nourishment of itself; it mixes with the blood, of
which it forms a material part, and is the means of conveying _the
nourishment of the blood_ to every part of the system. After it
has filled this office, and taken up impurities that are required
to be removed, it is cast out of the system again, without
undergoing any chemical change.

Man's body is to his Soul, in many respects, what a house is to
its occupant. But how superior is the dwelling which God erected,
to that which man has built. Reader, come out of yourself, and in
imagination realise the abstraction of the Soul from the body.
Make an effort of thought, and do not relinquish that effort,
until you fancy that you see your image seated on a chair before
you. And now proceed to ask yourself certain questions respecting
your bodily tenement--questions which, perchance, have never
occurred to you before; but which will impress themselves the more
forcibly upon you, in proportion as you realise for a moment the
idea of your Soul examining the body which it inhabits. There sits
before you a form of exquisite proportions, with reference to the
mode of life it has to pursue--the wants of the Soul for which it
has to care, and which it has to guard, under the direction of
that Soul, its owner and master.

Over the brows that mark the intellectual front of that due
form, there fall the auburn locks of youth, or the grey hair of
venerable age. Each of those hairs is curiously organised. If you
take a branch of a tree, and cut it across, you will find curious
markings caused by vessels of various structure, all necessary to
the existence of the plant. In the centre will be found either
a hollow tube, or a space occupied by a soft substance called
pith. Each hair of your head is as curiously formed as the branch
of a tree, and in a manner not dissimilar, though its parts
are so minute that the unaided eye cannot discern them. Every
hair has a root, just as a tree has, and through this root it
receives its nourishment. As the vessel which feed a plant are
always proportionate to the size of the plant itself, how fine
must be those vessels which form the roots of the hair, being in
proportion to the size of the hair, which is in itself so small
that the eye cannot see its structure? The hair is, in fact, an
animal plant, growing upon the body in much the same manner that
plants grow upon the surface of the earth. But how does this hair
grow? Not alone by the addition of matter at its roots, pushing up
and elongating its stem: nourishment passes up through its whole
length, and is deposited upon its end, just as the nourishment of
a tree is deposited upon its extreme branches. If, after having
your hair cut, you were to examine its ends by the microscope, you
would discover the abrupt termination left by the scissors. But
allow the hair to grow, and then examine it, and you will discover
that it grows from its point which, in comparison with its former
state, is perfect and fine. The reason why the beard is so hard
is, that the ends of the hair are continually being shaved off.
The hair of the beard, if allowed to grow, would become almost as
soft as the hair of the head.

[Verse: "The very hairs of your head are all numbered."--MATTHEW XI.]

But why is man's head thus covered with hair? For precisely the
same reason that a house is thatched--to keep the inmates warm.
We might add, also, to give beauty to the edifice. But as beauty
is a conventional quality--and if men were without it they would
consider themselves quite as handsome as they do now--we will not
enlarge upon the argument. Our bald-headed friends, too, might
have reason to complain of such a partial hypothesis. The brain
is the great organ upon which the health, the welfare, and the
happiness of the system depends. The skull, therefore, may be
regarded as analogous to the "strong box," the iron chest in which
the merchant keeps his treasure. There is no point at which the
brain can be touched to its injury, without first doing violence
to the skull. Even the spinal cord runs down the back through a
tunnel or tube, formed in a number of strong bones, so closely
and firmly jointed together, that they are commonly termed "the
back-bone."

Look at the eyebrows. What purpose do they fulfil? Precisely that
of a shed, or arch placed over a window to shelter it from rain.
But for the eyebrows the perspiration would frequently run from
the brow into the eyes, and obscure the sight; a man walking in a
shower of rain would scarcely be able to see; and a mariner in a
storm would find a double difficulty in braving the tempest.

Now we come to the eye, which is the window of the Soul's abode.
And what a window! how curiously constructed! how wisely guarded!
In the eyelashes, as well as the eyebrows, we see the hair
fulfilling a useful purpose, differing from any already described.
The eyelashes serve to keep cold winds, dust, and too bright
sun, from injuring or entering the windows of the body. When we
walk against the east wind, we bring the tips of our eyelashes
together, and in that way exclude the cold air from the surface
of the eye; and in the same manner we exclude the dust and modify
the light. The eyelashes, therefore, are like so many sentries,
constantly moving to and fro, protecting a most important organ
from injury. The eyelids are the shutters by which the windows
are opened and closed. But they also cleanse the eye, keeping it
bright and moist. There are, moreover, in the lids of each eye
or window, little glands, or springs, by which a clear fluid is
formed and supplied for cleansing the eye. The eye is placed in a
socket of the skull, in which it has free motion, turning right
or left, up or down, to serve the purpose of the inhabitant of
the dwelling. Of the structure of the eye itself we will not say
much, for the engravings will afford a clearer understanding than
a lengthy written description. But we would have you examine the
formation of the iris of the living eye, the ring which surrounds
the pupil. Hold a light to it, and you will find that the iris
will contract and diminish the pupil; withdraw the light, and the
iris will relax, and the pupil expand, thus regulating the amount
of light. The images of external objects are formed upon the
retina of the eye, a thin membrane, spread out upon the extremity
of a large nerve, which proceeds immediately to the brain, and
forms the telegraphic cord by which information is given to the
mind, of everything visible going on within the range of sight.

[Verse: "Thou art of purer eyes than to behold evil, and canst not look on iniquity."--HABAKKUK I.]

Now, think for a few moments upon the wonderful structure of those
windows of the body. Can you fancy, in the walls of your house, a
window which protects itself, cleanses itself, and turns in any
direction at the mere will of the tenant; and when that tenant is
oppressed by excess of light, draws its own curtain, and gives
him ease; and when he falls asleep, closes its own shutters, and
protects itself from the cold and dust of night, and the instant
he awakes in the morning, opens, cleanses itself with a fluid
which it has prepared during the night, and kept in readiness; and
repeats this routine of duty day after day for half a century,
without becoming impaired? Such, nevertheless, is the wonderful
structure of the window of the body--the eye.

In some scientific works that have recently been published,
curious investigations have been made known. It has been shown
that the eye is impressed momentarily, as a photographic plate
is impressed by the rays of the sun. But the photography of the
eye has this extraordinary quality--that one image passes away,
and another takes its place immediately, without confusion or
indistinctness. But the most wonderful assertion of all is, that
under the excitement of memory these photographic images are
restored; and that when, "in our mind's eye," we see the image
of some dear departed friend, the retina really revives an image
which once fell upon its sensitive surface, and which image has
been stored up for many years in the sacred portfolio of its
affections!

Another extraordinary assertion is one which comes supported by
a degree of authenticity that entitles it to consideration. It
is said that the eye of a dead man retains an impression of the
last picture that fell upon the faithful retina. Dr. Sandford, of
America, examined the eye of a man named Beardley, who had been
murdered at Auburn, and he published in the _Boston Atlas_ the
following statement:--"At first we suggested the saturation of the
eye in a weak solution of atrophine, which evidently produced an
enlarged state of the pupil. On observing this, we touched the end
of the optic nerve with the extract, when the eye instantly became
protuberant. We now applied a powerful lens, and discovered in the
pupil, the rude, worn-away figure of a man, with a light coat,
beside whom was a round stone, standing or suspended in the air,
with a small handle, stuck in the earth. The remainder was debris,
evidently lost from the destruction of the optic nerve, and its
separation from the mother brain. Had we performed the operation
when the eye was entire in the socket, with all its powerful
connection with the brain, there is not the least doubt but that
we should have detected the last idea and impression made on the
mind and eye of the unfortunate man. The picture would evidently
be entire; and perhaps we should have had the contour, or better
still, the exact figure of the murderer. The last impression on
the brain before death is always more terrible from fear than any
other cause, and figures impressed on the pupil more distinct,
which we attribute to the largeness of the optic nerve, and its
free communication with the brain." Whether the supposition, which
seems to be supported by the experiment above detailed, be correct
or not, it is in no sense more wonderful than the facts which are
already known respecting this curious and perfect organ.

[Verse: "Be not rash with thy mouth, and let not thine heart be hasty to utter anything before God: for God is in heaven, and thou upon earth; therefore let thy words be few."--ECCLESIASTES V.]

The nose is given us for two purposes--to enable us to respire and
to smell. As odours arise from the surface of the earth, the cup
or funnel of the nose is turned down to meet them. In the nostrils
hair again serves a useful purpose. It not only warms the air
which enters the nostrils, but it springs out from all sides, and
forms an intersecting net, closing the nostrils against dust, and
the intrusion of small insects. If by any means, as when taking
a sharp sniff, foreign matters enter the nostrils, the nose is
armed with a set of nerves which communicate the fact to certain
muscles, and the organs of respiration unite with those muscles to
expel the intruding substances. In this action, the diaphragm, or
the muscle which divides the abdomen from the chest, is pressed
down, the lungs are filled with air, the passage by which that
air would otherwise escape through the mouth, is closed up, and
then, all at once, with considerable force, the air is pressed
through the nostrils, to free them from the annoying substance. So
great is the force with which this action takes place, that the
passage into the mouth is generally pushed open occasioning the
person in whom the action takes place, to cry "'tsha!" and thus
is formed what is termed a sneeze. As with the eye, so with the
nose--innumerable nerves are distributed over the lining membrane,
and these nerves are connected with larger nerves passing to the
brain, through which everything relating to the sense of smell is
communicated.

The nose acts like a custom-house officer to the system. It is
highly sensitive to the odour of most poisonous substances. It
readily detects hemlock, henbane, monk's hood, and the plants
containing prussic acid. It recognises the foeted smell of
drains, and warns us not to breathe the polluted air. The nose
is so sensitive, that air containing a 200,000th part of bromine
vapour will instantly be detected by it. It will recognise the
1,300,000th part of a grain of otto of roses, or the 13,000,000th
part of a grain of musk! It tells us in the mornings that our
bed-rooms are impure; it catches the first fragrance of the
morning air, and conveys to us the invitation of the flowers to go
forth into the fields, and inhale their sweet breath. To be "led
by the nose," has hitherto been used as a phrase of reproach. But
to have a good nose, and to follow its guidance, is one of the
safest and shortest ways to the enjoyment of health.

The mouth answers the fourfold purpose of the organ of taste,
of sound, of mastication, and of breathing. In all of these
operations, except in breathing, the various parts of the mouth
are engaged. In eating we use the lips, the tongue, and the teeth.
The teeth serve the purpose of grinding the food, the tongue
turns it during the process of grinding, and delivers it up to
the throat for the purposes of the stomach, when sufficiently
masticated. The lips serve to confine the food in the mouth, and
assist in swallowing it, and there are glands underneath the
tongue, and in the sides of the mouth, which pour in a fluid
to moisten the food. And so watchful are those glands of their
duty, that the mere imagination frequently causes them to act.
Their fluid is required to modify the intensity of different
flavours and condiments in which man, with his love of eating,
will indulge. Thus, when we eat anything very acid, as a lemon, or
anything very irritating, as Cayenne pepper, the effect thereof
upon the sensitive nerves of the tongue is greatly modified by a
free flow of saliva into the mouth. And if we merely fancy the
taste of any such things, those glands are so watchful, that they
will immediately pour out their fluid to mitigate the supposed
effect.

[Verse: "I say unto you, Swear not at all; neither by heaven, for it is God's throne; Nor by the earth; for it is his footstool."--MATTHEW V.]

In speaking, we use the lips, the teeth, the tongue; and the
chest supplies air, which, being controlled in its emission, by
a delicate apparatus at the mouth of the wind-pipe, causes the
various sounds which we have arranged into speech, and by which,
under certain laws, we are enabled to understand each other's
wants, participate in each other's emotions, express our loves,
our hopes, our fears, and glean those facts, the accumulation of
which constitutes knowledge, enhances the happiness of man, and
elevates him, in its ultimate results above the lower creatures to
which the blessing of speech is denied.

The curious structure of the tongue, and the organs of speech,
would fill a very interesting volume. The tongue is unfortunately
much abused, not only by those who utter foul words, and convert
the blessing of speech, which should improve and refine, into
a source of wicked and profane language; but it constantly
remonstrates against the abuse of food, and the use of things
which are not only unnecessary for the good of our bodies, but
prejudicial to their health. When the body is sufficiently fed,
the tongue ceases its relish, and derives no more satisfaction
from eating: but man contrives a variety of inventions to whip the
tongue up to an unnatural performance of its duty, and thus we not
only over-eat, but eat things that have no more business in our
stomachs, than have the stones that we walk upon. Can we wonder,
then, that disease is so prevalent, and that death calls for many
of us so soon.

That wonderful essence, the Soul of man, rises above all finite
knowledge. Its wonders and powers will never, probably, be
understood until when, in a future state of existence, the
grandest of all mysteries shall be explained. When we talk of the
brain, we speak of that which it is easy to comprehend as the
organ, or the seat of the mind; when we speak of the mind, we
have greater difficulty in comprehending the meaning of the term
we employ; but when we speak of the Soul, we have reached a point
which defies our understanding, because our knowledge is limited.
The brain may be injured by a blow; the mind may be pained by a
disagreeable sight, or offended by a harsh word; but the Soul
can only be influenced secondarily through the mind, which is
primarily affected by the organs of the material senses. Thus the
happiness or the misery of the Soul depends to a very great extent
upon the proper fulfilment of the duties of the senses, which are
the servants of the Soul, over which the mind presides, as the
steward who mediates between the employer and the employed.

The Ear, which is taught to delight in sweet sounds, and in pure
language, is a better servant of the master Soul, than one which
delights not in music, and which listens, with approbation or
indifference, to the oaths of the profane. The Eye which rejoices
in the beauties of nature, and in scenes of domestic happiness
and love, is a more faithful servant than one that delights in
witnessing scenes of revelry, dissipation, and strife. The Nose
which esteems the sweet odour of flowers, or the life-giving
freshness of the pure air, is more dutiful to his master than one
that rejects not the polluted atmosphere of neglected dwellings.
The Mouth which thirsts for morbid gratification of taste, is more
worthless than one which is contented with wholesome viands, and
ruled by the proper instincts of its duty. Who that can understand
the wonderful structure of the tongue, and the complicated
mechanism of the organs of speech and of hearing, could be found
to take pleasure in the utterance of oaths, and of words of vulgar
meaning? Were those beautiful cords that like threads of silk are
woven into the muscular texture of the mouth, and along which
the essence of life travels with the quickness of thought, to do
the bidding of the will--were they given for no higher use than
to sin against the God who gave them, and upon whose mercy their
existence every moment depends?

[Verse: "Out of the same mouth proceedeth blessing and cursing. My brethren, these things ought not so to be."--JAMES III.]

The actions of the senses must necessarily affect the mind, which
is the head steward of the Soul; and the Soul becomes rich in
goodness, or poor in sin, in proportion as the stewardship, held
by his many servants, is rightly or wrong-fully fulfilled. As in
an establishment where the servants are not properly directed
and ruled, they often gain the ascendancy, and the master has no
power over them, so with man, when he gives himself up to sensual
indulgences. The Soul becomes the slave of the senses--the master
is controlled by the servants.

With regard to the mechanism of motion, let us take the case of
a man who is walking a crowded thoroughfare, and we shall see
how active are all the servants of the Soul, under the influence
of the mind. He walks along in a given direction. But for the
act of volition in the mind, not a muscle would stir. The eye
is watching his footsteps. There is a stone in his path, the
eye informs the mind, the mind communicates with the brain, and
the nerves stimulate the muscles of the leg to lift the foot a
little higher, or turn it on one side, and the stone is avoided.
The eye alights on a familiar face, and the mind remembers that
the eye has seen that face before. The man goes on thinking of
the circumstance under which he saw that person, and partially
forgets his walk, and the direction of his steps. But the nerves
of volition and motion unite to keep the muscles up to their work,
and he walks on without having occasion to think continually,
"I must continue walking." He has not to make an effort to lift
his leg along between each interval of meditation; he walks and
meditates the while. Presently a danger approaches him from
behind. The eye sees it not--knows no more, in fact, than if it
were dead. But the ear sounds the alarm, tells the man, by the
rumbling of a wheel, and the tramp of horses' feet, that he is in
danger; and then the nerves, putting forth their utmost strength,
whip the muscles up to the quick performance of their duty; the
man steps out of the way of danger, and is saved. He draws near
to a sewer, which is vomiting forth its poisonous exhalations.
The eye is again unconscious--it cannot see the poison lurking in
the air. The ear, too, is helpless; it cannot bear witness to the
presence of that enemy to life. But the nose detects the noxious
agent, and then the eye points out the direction of the sewer, and
guides his footsteps to a path where he may escape the injurious
consequences. A clock strikes, the ear informs him that it is the
hour of an appointment; the nerves stimulate the muscles again,
and he is hastened onward. He does not know the residence of his
friend, but his tongue asks for him, and his ear makes known the
reply. He reaches the spot--sits--rests. The action of the muscles
is stayed; the nerves are for a time at rest. The blood which
had flown freely to feed the muscles while they were working,
goes more steadily through the arteries and veins, and the lungs,
which had been purifying the blood in its course, partake of the
temporary rest.

[Verse: "I am but a little child: I know not how to go out or come in."--I KINGS III.]

Let us remember that there are two sets of muscles, acting in
unison with each other, to produce the various motions; they are
known by the general terms of _flexors_ and _extensors_; the first
enable us to bend the limbs, the other to bring the limbs back to
their former position. The flexors enable us to close the hand,
the extensors to open it again. The flexors enable us to raise the
foot from the ground; the extensors set the foot down again in the
place desired. Consider for a moment the nicety with which the
powers of these muscles must be balanced, and the harmony which
must subsist between them in their various operations. When we
are closing the hand, if the extensor muscles did not gradually
yield to the flexors--if they gave up their hold all at once, the
hand, instead of closing with gentleness and ease, would be jerked
together in a sudden and most uncomfortable manner. If, in such
a case, you were to lay your hand with its back upon the table,
and wish to close the hand, the fingers would fall down upon the
palm suddenly, like the lid of a box. Again, consider how awkward
it would be in such a case; our walk through the streets would
become a series of jumps and jerks; when a man had raised his
foot, after it had been jerked up, there it would stand fixed for
a second before the opposite muscles could put on their power to
draw it down again. This case is not at all suppositious: there is
a derangement frequently observed in horses, in which one set of
muscles becomes injured, and we may see horses suffering from this
ailment, trotting along with one of their legs jerking up much
higher than the others, and set down again with difficulty, just
in the manner described.

It is also to be observed that very nice proportions must exist
between the sizes of the muscles and the sizes of the bones. If
this were not the case, our motions, instead of being firm and
steady, would be all shaky and uncertain. In old persons the
muscles become weak and relaxed; hence there is a tendency in the
movements of the aged to fall, as it were, together; the head is
no longer erect, the body bends, the knees totter, and the arms
lean towards the body as for support.

In the child a somewhat similar state of things exists. The
muscles have not been properly developed, nor have they been
brought sufficiently under the controul of the nervous system. The
child, therefore, totters and tumbles about, and it is not until
it has stumbled and tumbled some hundreds of times in its little
history, that the muscles have become strong enough to fulfil
their office, or have been brought sufficiently under the controul
of the nervous system, to perform well the various duties required
from them.

In all these things, we recognise the perfection of the divine
works. We are apt, too apt, to overlook this perfection,
because it prevails in everything; but by speculating upon what
inconveniences we might suffer, were not things ordained as they
are, we obtain most convincing evidences of divine goodness and
wisdom.

[Verse: "Watchman, what of the night? The watchman said, The morning cometh, and also the night; if ye will enquire, enquire ye; return, come."--ISAIAH XXI.]

Having taken this view of the muscular system of the external
man, let us turn our attention to the muscles of the internal
organs. The muscles of which we have been speaking are called
the voluntary muscles, because we have them under our own
controul--they are subject to the influences of our will. But
there is the other set of muscles. What are they? We talk of the
beating, or of the palpitation, of the heart. But, what is it
that causes the heart to beat? You cannot, if you wish it, make
your heart beat more quickly or more slowly. Place your finger
upon your pulse, and notice the degree of rapidity with which its
pulsations follow. Now think that you should like to double the
frequency of those pulsations. Say to the heart, with your inner
voice, that you wish it to beat 120 times in a minute, instead of
60. It does not obey you; it does not appreciate your command.
Now place your finger on the table, and your watch by the side of
your hand, and tell your finger to beat 60 times in the minute,
or 100 times, or 150 times, or 200 times, and the finger will
obey you--because it is _moved by muscles which are subject to
the will_, while the heart is composed of muscles which are _not
subject to the will_. Why should this be? Why should man have the
power to regulate his finger, and not to regulate his heart?

For the sustentation of our bodies it is needful that the blood
should ever be in circulation. If the heart were to cease beating
only for three or four minutes (perhaps less) life would be
extinct. In this short time the whole framework of man, beautiful
in its proportions, perfect in its parts, would pass into the
state of dead matter, and would simply wait the decay that follows
death. The eye would become dull and glazed, the lips would turn
blue, the skin would acquire the coldness of clay--love, hope,
joy, would all cease. The sweetest, the fondest ties would be
broken. Flowers might bloom, and yield their fragrance, but
they would be neither seen nor smelt; the sun might rise in its
brightest splendour, yet the eye would not be sensitive to its
rays; the rosy-cheeked child might climb the paternal knee; but
there, stiff, cold, without joy, or pain, or emotion of any kind,
unconscious as a block of marble, would sit the man _whose heart
for a few moments had ceased to beat_.

How wise, then, and how good of God, that he has not placed
this vital organ under our own care! How sudden would be our
bereavements--how frequent our deaths, how sleepless our nights,
and how anxious our days, if we had to keep our own hearts at
work, and death the penalty of neglect.

And yet, before we were born, until we reach life's latest
moment--through days of toil, and nights of rest--even in the
moments of our deepest sin against the God who at the time is
sustaining us, our hearts beat on, never stopping, never wearying,
never asking rest.

This brings us to another reflection. Our arms get weary, our
legs falter from fatigue, the mind itself becomes overtaxed,
and all our senses fall to sleep. The eye sees not, the ear is
deaf to sound, the sentinels that surround the body, the nerves
of touch, are all asleep--you may place your hand upon the brow
of the sleeping man, and he feels it not. Yet, unseen, unheard,
without perceptible motion, or the slightest jar to mar the rest
of the sleeper, the heart beats on, and on, and on. As his sleep
deepens, the heart slackens its speed, that his rest may be the
more sound. He has slept for eight hours, and the time approaches
for his awakening. But is the heart weary--that heart which has
toiled through the long and sluggard night? No! The moment the
waking sleeper moves his arm, the heart is aware that a motion has
been made, that effort and exercise are about to begin. The nerves
are all arousing to action; the eyes turn in their sockets, the
head moves upon the neck; the sleeper leaves his couch, and the
legs are once more called upon to bear the weight of the body.
Blood is the food of the eye, the food of the ear, of the foot,
the hand, and every member of the frame. While they labour they
must be fed--that is the condition of their life, the source of
their strength. The heart, therefore, so far from seeking rest, is
all fresh and vigorous for the labours of the day, and proceeds to
discharge its duty so willingly, that we do not even know of the
movements that are going on within us.

[Verse: "Awake up, my glory; awake, psaltery and harp: I myself will awake early."--PSALM LVII.]

Thus we have seen the difference between the voluntary and the
involuntary muscles, and we have perceived the goodness of our
Creator in not entrusting to our keeping the controul of an organ
so vital to life, as the heart.

But the heart is not the only organ which thus works unseen and
unfelt. There are the lungs and the muscles of the chest, the
stomach, and other parts occupying the abdomen, together with all
those muscular filaments which enter into the structure of the
coats and valves of the blood-vessels, and which assist to propel
the blood through the system. All these are at work at every
moment of man's life; and yet, so perfect is this complicated
machinery, that we really do not know, except by theory, what is
going on within us.

During the time that the sleeper has been at rest, the stomach has
been at work digesting the food which was last eaten. Then the
stomach has passed the macerated food into the alimentary canal,
the liver has poured out its secretion, and produced certain
changes in the condition of the dissolved food: and the lacteals,
of which there may be many thousands, perhaps millions, have been
busy sucking up those portions of the food which they knew to be
useful to the system, whilst they have rejected all those useless
and noxious matters upon which the liver, like an officer of
health, had set his mark, as unfitting for the public use. This
busy life has gone on uninterruptedly; every member of that body,
every worker in that wonderful factory, has been unremitting in
his duty, and yet the owner, the master, has been asleep, and
wakes up finding every bodily want supplied!

Notwithstanding that much has already been said of the wonders
that pertain to the eye, it has not yet been considered as the
seat of _tears_, those mute but eloquent utterers of the sorrows
of the heart. Beautiful Tear! whether lingering upon the brink
of the eyelid, or darting down the furrows of the care-worn
cheek--thou art sublime in thy simplicity--great, because of thy
modesty--strong, from thy very weakness. Offspring of sorrow! who
will not own thy claim to sympathy? who can resist thy eloquence?
who can deny mercy when thou pleadest?

Every tear represents some in-dwelling sorrow preying upon the
mind and destroying its peace. The tear comes forth to declare the
inward struggle, and to plead a truce against further strife. How
meet that the eye should be the seat of tears--where they cannot
occur unobserved, but, blending with the beauty of the eye itself,
must command attention and sympathy!

Whenever we behold a tear, let our kindliest sympathies awake--let
it have a sacred claim upon all that we can do to succour and
comfort under affliction. What rivers of tears have flown,
excited by the cruel and perverse ways of man! War has spread its
carnage and desolation, and the eyes of widows and orphans have
been suffused with tears! Intemperance has blighted the homes of
millions, and weeping and wailing have been incessant! A thousand
other evils which we may conquer have given birth to tears enough
to constitute a flood--a great tide of grief. Suppose we prize
this little philosophy, _and each one determine never to excite a
tear in another_. Watching the eye as the telegraph of the mind
within, let us observe it with anxious regard; and whether we are
moved to complaint by the existence of supposed or real wrongs,
let the indication of the coming tear be held as a sacred truce to
unkindly feeling, and our efforts be devoted to the substitution
of smiles for tears!

[Verse: "Who is as the wise man? and who knoweth the interpretation of a thing? a man's wisdom maketh his face to shine, and the boldness of his face shall be changed."--ECCLESIASTES VIII.]

There is only one other matter to which we think it necessary
to allude, before we pass to the concluding section of our
work. It has been said (162), that snow which is _white_, keeps
the earth warm; that _white_ as a colour is _cool_, and that
_black_ absorbs _heat_ (230). These assertions may appear to be
contradictory, and, taken in connection with the fact of the
blackness of the skin of negroes in hot climates, may at a first
glance be considered unsatisfactory. They are, however, perfectly
reconcileable, and that too, without the slightest evasion of
the real bearing of the asserted facts. White snow is warm _on
account of its texture_, which, being woolly, forms a layer of
non-conducting substance over the surface of the earth, and _keeps
in its warmth_; white clothing, worn as a garment consisting
of a thin material, is cool, because _the white colour_ turns
back the rays of the sun that fall upon it. Swansdown, although
white, being a non-conductor, would be warm, because, though it
would reflect the light and heat, it would confine and accumulate
the heat of the body. The black skin of the negro is a _living
texture_, and is not subject to the same laws that govern dead
matter. The skin of the negro is largely provided with cells
which secrete a fatty matter that acts as a non-conductor of the
_external_ heat, and also a much larger number of perspiratory
glands than exist in the skins of Europeans. The perspiration
cools the blood, and carries off the _internal_ heat, while the
oily matter gives a shining surface to the skin, and reflects
the heat, to which the fatty matter presents itself as a
non-conductor. We see, therefore, that there are two express
provisions for the cooling of the negroes' skin, independent of
the colour. The skin of the Esquimaux who inhabits a cold country
is _white_, though it might be supposed that a black skin would
best conduce to the warmth of his body. But the Esquimaux has,
underneath his skin, _a thick coating of fat_, by which the
_internal heat_ of the body is prevented from escaping.

This _resume_ of the subjects embodied in the form of question
and answer in the previous pages, will serve to impress the more
important truths upon the mind of the reader, while it has enabled
us to fill up many omissions necessitated by the arbitrary form of
catechetical composition.

[Verse: "Ask now the beasts, and they shall teach thee; and the fowls of the air, and they shall tell thee."--JOB XII.]