Thoughts on Man

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"From what we know of our own system, it may be reasonably
concluded, that all the rest are with equal wisdom contrived,
situated, and provided with accommodations for rational
inhabitants.

"What a sublime idea does this suggest to the human imagination,
limited as are its powers, of the works of the Creator!
Thousands and thousands of suns, multiplied without end, and
ranged all around us, at immense distances from each other,
attended by ten thousand times ten thousand worlds, all in rapid
motion, yet calm, regular and harmonious, invariably keeping the
paths prescribed them: and these worlds peopled with myriads of
intelligent beings, formed for endless progression in perfection
and felicity!"

The thought that would immediately occur to a dispassionate man
in listening to this statement, would be, What a vast deal am I
here called on to believe!

Now the first rule of sound and sober judgment, in encountering
any story, is that, in proportion to the magnitude and seemingly
incredible nature of the propositions tendered to our belief,
should be the strength and impregnable nature of the evidence by
which those propositions are supported.

It is not here, as in matters of religion, that we are called
upon by authority from on high to believe in mysteries, in things
above our reason, or, as it may be, contrary to our reason. No
man pretends to a revelation from heaven of the truths of
astronomy. They have been brought to light by the faculties of
the human mind, exercised upon such facts and circumstances as
our industry has set before us.

To persons not initiated in the rudiments of astronomical
science, they rest upon the great and high-sounding names of
Galileo, Kepler, Halley and Newton. But, though these men are
eminently entitled to honour and gratitude from their
fellow-mortals, they do not stand altogether on the same footing
as Matthew, Mark, Luke and John, by whose pens has been recorded
"every word that proceedeth out of the mouth of God."

The modest enquirer therefore, without pretending to put himself
on an equality with these illustrious men, may be forgiven, when
he permits himself to suggest a few doubts, and presumes to
examine the grounds upon which he is called upon to believe all
that is contained in the above passages.

Now the foundations upon which astronomy, as here delivered, is
built, are, first, the evidence of our senses, secondly, the
calculations of the mathematician, and, in the third place, moral
considerations. These have been denominated respectively,
practical astronomy, scientific, and theoretical.

As to the first of these, it is impossible for us on this
occasion not to recollect what has so often occurred as to have
grown into an every-day observation, of the fallibility of our
senses.

It may be doubted however whether this is a just statement. We
are not deceived by our senses, but deceived in the inference we
make from our sensations. Our sensations respecting what we call
the external world, are chiefly those of length, breadth and
solidity, hardness and softness, heat and cold, colour, smell,
sound and taste. The inference which the generality of mankind
make in relation to these sensations is, that there is something
out of ourselves corresponding to the impressions we receive; in
other words, that the causes of our sensations are like to the
sensations themselves. But this is, strictly speaking, an
inference; and, if the cause of a sensation is not like the
sensation, it cannot precisely be affirmed that our senses
deceive us. We know what passes in the theatre of the mind; but
we cannot be said absolutely to know any thing, more.

Modern philosophy has taught us, in certain cases, to controvert
the position, that the causes of our sensations are like to the
sensations themselves. Locke in particular has called the
attention of the reasoning part of mankind to the consideration,
that heat and cold, sweet and bitter, and odour offensive or
otherwise, are perceptions, which imply a percipient being, and
cannot exist in inanimate substances. We might with equal
propriety ascribe pain to the whip that beats us, or pleasure to
the slight alternation of contact in the person or thing that
tickles us, as suppose that heat and cold, or taste, or smell are
any thing but sensations.

The same philosophers who have called our attention to these
remarks, have proceeded to shew that the causes of our sensations
of sound and colour have no precise correspondence, do not tally
with the sensations we receive. Sound is the result of a
percussion of the air. Colour is produced by the reflection of
the rays of light; so that the same object, placed in a position,
different as to the spectator, but in itself remaining unaltered,
will produce in him a sensation of different colours, or shades
of colour, now blue, now green, now brown, now black, and so on.
This is the doctrine of Newton, as well as of Locke.

It follows that, if there were no percipient being to receive
these sensations, there would be no heat or cold, no taste, no
smell, no sound, and no colour.

Aware of this difference between our sensations in certain cases
and the causes of these sensations, Locke has divided the
qualities of substances in the material universe into primary and
secondary, the sensations we receive of the primary representing
the actual qualities of material substances, but the sensations
we receive of what he calls the secondary having no proper
resemblance to the causes that produce them.

Now, if we proceed in the spirit of severe analysis to examine
the primary qualities of matter, we shall not perhaps find so
marked a distinction between those and the secondary, as the
statement of Locke would have led us to imagine.

The Optics of Newton were published fourteen years later than
Locke's Essay concerning Human Understanding.

In endeavouring to account for the uninterrupted transmission of
rays of light through transparent substances, however hard they
may be found to be, Newton has these observations.

"Bodies are much more rare and porous, than is commonly believed.

Water is nineteen times lighter, and by consequence nineteen
times rarer, than gold; and gold is so rare, as very readily, and
without the least opposition, to transmit the magnetic effluvia,
and easily to admit quicksilver into its pores, and to let water
pass through it. From all which we may conclude, that gold has
more pores than solid parts, and by consequence that water has
above forty times more pores than parts. And he that shall find
out an hypothesis, by which water may be so rare, and yet not
capable of compression by force, may doubtless, by the same
hypothesis, make gold, and water, and all other bodies, as much
rarer as he pleases, so that light may find a ready passage
through transparent substances[43]."

[43] Newton, Optics, Book II, Part III, Prop. viii.

Again: "The colours of bodies arise from the magnitude of the
particles that reflect them. Now, if we conceive these particles
of bodies to be so disposed among themselves, that the intervals,
or empty spaces between them, may be equal in magnitude to them
all; and that these particles may be composed of other particles
much smaller, which have as much empty space between them as
equals all the magnitudes of these smaller particles; and that in
like manner these smaller particles are again composed of others
much smaller, all which together are equal to all the pores, or
empty spaces, between them; and so on perpetually till you come
to solid particles, such as have no pores, or empty spaces within
them: and if in any gross body there be, for instance, three
such degrees of particles, the least of which are solid; this
body will have seven times more pores than solid parts. But if
there be four such degrees of particles, the least of which are
solid, the body will have fifteen times more pores than solid
parts. If there be five degrees, the body will have one and
thirty times more pores than solid parts. If six degrees, the
body will have sixty and three times more pores than solid parts.

And so on perpetually[44]."

[44] Ibid.

In the Queries annexed to the Optics, Newton further suggests an
opinion, that the rays of light are repelled by bodies without
immediate contact. He observes that:

"Where attraction ceases, there a repulsive virtue ought to
succeed. And that there is such a virtue, seems to follow from
the reflexions and inflexions of the rays of light. For the rays
are repelled by bodies, in both these cases, without the
immediate contact of the reflecting or inflecting body. It seems
also to follow from the emission of light; the ray, so soon as it
is shaken off from a shining body by the vibrating motion of the
parts of the body, and gets beyond the reach of attraction, being
driven away with exceeding great velocity. For that force, which
is sufficient to turn it back in reflexion, may be sufficient to
emit it. It seems also to follow from the production of air and
vapour: the particles, when they are shaken off from bodies by
heat or fermentation, so soon as they are beyond the reach of the
attraction of the body, receding from it and also from one
another, with great strength; and keeping at a distance, so as
sometimes to take up a million of times more space than they did
before, in the form of a dense body."

Newton was of opinion that matter was made up, in the last
resort, of exceedingly small solid particles, having no pores, or
empty spaces within them. Priestley, in his Disquisitions
relating to Matter and Spirit, carries the theory one step
farther; and, as Newton surrounds his exceedingly small particles
with spheres of attraction and repulsion, precluding in all cases
their actual contact, Priestley is disposed to regard the centre
of these spheres as mathematical points only. If there is no
actual contact, then by the very terms no two particles of matter
were ever so near to each other, but that they might be brought
nearer, if a sufficient force could be applied for that purpose.
You had only another sphere of repulsion to conquer; and, as
there never is actual contact, the whole world is made up of one
sphere of repulsion after another, without the possibility of
ever arriving at an end.

"The principles of the Newtonian philosophy," says our author,
"were no sooner known, than it was seen how few in comparison, of
the phenomena of nature, were owing to solid matter, and how much
to powers, which were only supposed to accompany and surround the
solid parts of matter. It has been asserted, and the assertion
has never been disproved, that for any thing we know to the
contrary, all the solid matter in the solar system might be
contained within a nutshell[45]."

[45] Priestley, Disquisitions, Section II. I know not by whom
this illustration was first employed. Among other authors, I
find, in Fielding (Joseph Andrews, Book II, Chap. II), a sect of
philosophers spoken of, who "can reduce all the matter of the
world into a nutshell."

It is then with senses, from the impressions upon which we are
impelled to draw such false conclusions, and that present us with
images altogether unlike any thing that exists out of ourselves,
that we come to observe the phenomena of what we call the
universe. The first observation that it is here incumbent on us
to make, and which we ought to keep ever at hand, to be applied
as occasion may offer, is the well known aphorism of Socrates,
that "we know only this, that we know nothing." We have no
compass to guide us through the pathless waters of science; we
have no revelation, at least on the subject of astronomy, and of
the unnumbered inhabitable worlds that float in the ocean of
ether; and we are bound therefore to sail, as the mariners of
ancient times sailed, always within sight of land. One of the
earliest maxims of ordinary prudence, is that we ought ever to
correct the reports of one sense by the assistance of another
sense. The things we here speak of are not matters of faith; and
in them therefore it is but reason, that we should imitate the
conduct of Didymus the apostle, who said, "Except I put my
fingers into the prints of the nails, and thrust my hand into his
side, I will not believe." My eyes report to me an object, as
having a certain magnitude, texture, and roughness or smoothness;
but I require that my hands should confirm to me the evidence of
my eyes. I see something that appears to be an island at an
uncertain distance from the shore; but, if I am actuated by a
laudable curiosity, and wish to possess a real knowledge, I take
a boat, and proceed to ascertain by nearer inspection, whether
that which I imagined to be an island is an island or no.

There are indeed many objects with which we are conversant, that
are in so various ways similar to each other, that, after having
carefully examined a few, we are satisfied upon slighter
investigation to admit the dimensions and character of others.
Thus, having measured with a quadrant the height of a tower, and
found on the narrowest search and comparison that the report of
my instrument was right, I yield credit to this process in
another instance, without being at the trouble to verify its
results in any more elaborate method.

The reason why we admit the inference flowing from our
examination in the second instance, and so onward, with less
scrupulosity and scepticism than in the first, is that there is a
strict resemblance and analogy in the two cases. Experience is
the basis of our conclusions and our conduct. I strike against a
given object, a nail for example, with a certain degree of force,
because I have remarked in myself and others the effect of such a
stroke. I take food and masticate it, because I have found that
this process contributes to the sound condition of my body and
mind. I scatter certain seeds in my field, and discharge the
other functions of an agriculturist, because I have observed that
in due time the result of this industry is a crop. All the
propriety of these proceedings depends upon the exact analogy
between the old case and the new one. The state of the affair is
still the same, when my business is merely that of an observer
and a traveller. I know water from earth, land from sea, and
mountains from vallies, because I have had experience of these
objects, and confidently infer that, when certain appearances
present themselves to my organs of sight, I shall find the same
results to all my other senses, as I found when such appearances
occurred to me before.

But the interval that divides the objects which occur upon and
under the earth, and are accessible in all ways to our
examination, on the one hand, and the lights which are suspended
over our heads in the heavens on the other, is of the broadest
and most memorable nature. Human beings, in the infancy of the
world, were contented reverently to behold these in their
calmness and beauty, perhaps to worship them, and to remark the
effects that they produced, or seemed to produce, upon man and
the subjects of his industry. But they did not aspire to measure
their dimensions, to enquire into their internal frame, or to
explain the uses, far removed from our sphere of existence, which
they might be intended to serve.

It is however one of the effects of the improvement of our
intellect, to enlarge our curiosity. The daringness of human
enterprise is one of the prime glories of our nature. It is our
boast that we undertake to "measure earth, weigh air, and state
the tides." And, when success crowns the boldness of our
aspirations after what vulgar and timorous prudence had
pronounced impossible, it is then chiefly that we are seen to
participate of an essence divine.

What has not man effected by the boldness of his conceptions and
the adventurousness of his spirit? The achievements of human
genius have appeared so incredible, till they were thoroughly
examined, and slowly established their right to general
acceptance, that the great heroes of intellect were universally
regarded by their contemporaries as dealers in magic, and
implements of the devil. The inventor of the art of printing,
that glorious instrument for advancing the march of human
improvement, and the discoverer of the more questionable art of
making gunpowder, alike suffered under this imputation. We have
rendered the seas and the winds instruments of our pleasure,
"exhausted the old world, and then discovered a new one," have
drawn down lightning from heaven, and exhibited equal rights and
independence to mankind. Still however it is incumbent on us to
be no less wary and suspicious than we are bold, and not to
imagine, because we have done much, that we are therefore able to
effect every thing.

As was stated in the commencement of this Essay, we know our own
sensations, and we know little more. Matter, whether in its
primary or secondary qualities, is certainly not the sort of
thing the vulgar imagine it to be. The illustrious Berkeley has
taught many to doubt of its existence altogether; and later
theorists have gone farther than this, and endeavoured to shew,
that each man, himself while he speaks on the subject, and you
and I while we hear, have no conclusive evidence to convince us,
that we may not, each of us, for aught we know, be the only thing
that exists, an entire universe to ourselves.

We will not however follow these ingenious persons to the
startling extreme to which their speculations would lead us.
But, without doing so, it will not misbecome us to be cautious,
and to reflect what we do, before we take a leap into illimitable
space.

SECTION II.

"The sun," we are told, "is a solid body, ninety-five millions of
miles distant from the earth we inhabit, one million times larger
in cubic measurement, and to such a degree impregnated with heat,
that a comet, approaching to it within a certain distance, was by
that approximation raised to a heat two thousand times greater
than that of red-hot iron."

It will be acknowledged, that there is in this statement much to
believe; and we shall not be exposed to reasonable blame, if we
refuse to subscribe to it, till we have received irresistible
evidence of its truth.

It has already been observed, that, for the greater part of what
we imagine we know on the surface or in the bowels of the earth,
we have, or may have if we please, the evidence of more than one
of our senses, combining to lead to the same conclusion. For the
propositions of astronomy we have no sensible evidence, but that
of sight, and an imperfect analogy, leading from those visible
impressions which we can verify, to a reliance upon those which
we cannot.

The first cardinal particular we meet with in the above statement
concerning the sun, is the term, distance. Now, all that,
strictly speaking, we can affirm respecting the sun and other
heavenly bodies, is that we have the same series of impressions
respecting them, that we have respecting terrestrial objects near
or remote, and that there is an imperfect analogy between the one
case and the other.

Before we affirm any thing, as of our own knowledge and
competence, respecting heavenly bodies which are said to be
millions of millions of miles removed from us, it would not
perhaps be amiss that we should possess ourselves of a certain
degree of incontestible information, as to the things which exist
on the earth we inhabit. Among these, one of the subjects
attended with a great degree of doubt and obscurity, is the
height of the mountains with which the surface of the globe we
inhabit is diversified. It is affirmed in the received books of
elementary geography, that the Andes are the highest mountains in
the world. Morse, in his American Gazetteer, third edition,
printed at Boston in 1810[46], says, "The height of Chimborazzo,
the most elevated point of the vast chain of the Andes, is 20,280
feet above the level of the sea, which is 7102 feet higher than
any other mountain in the known world:" thus making the elevation
of the mountains of Thibet, or whatever other rising ground the
compiler had in his thought, precisely 13,178 feet above the
level of the sea, and no more. This decision however has lately
been contradicted. Mr. Hugh Murray, in an Account of Discoveries
and Travels in Asia, published in 1820, has collated the reports
of various recent travellers in central Asia; and he states the
height of Chumularee, which he speaks of as the most elevated
point of the mountains of Thibet, as nearly 30,000 feet above the
level of the sea.

[46] Article, Andes.

The elevation of mountains, till lately, was in no way attempted
to be ascertained but by the use of the quadrant) and their
height was so generally exaggerated, that Riccioli, one of the
most eminent astronomers of the seventeenth century, gives it as
his opinion that mountains, like the Caucasus, may have a
perpendicular elevation of fifty Italian miles[47]. Later
observers have undertaken to correct the inaccuracy of these
results through the application of the barometer, and thus, by
informing themselves of the weight of the air at a certain
elevation, proceeding to infer the height of the situation.

[47] Rees, Encyclopedia; article, Mountains.

There are many circumstances, which are calculated to induce a
circumspect enquirer to regard the affirmative positions of
astronomy, as they are delivered by the most approved modern
writers, with considerable diffidence.

They are founded, as has already been said, next to the evidence
of our senses, upon the deductions of mathematical knowledge.

Mathematics are either pure or mixed.

Pure mathematics are concerned only with abstract propositions,
and have nothing to do with the realities of nature. There is no
such thing in actual existence as a mathematical point, line or
surface. There is no such thing as a circle or square. But that
is of no consequence. We can define them in words, and reason
about them. We can draw a diagram, and suppose that line to be
straight which is not really straight, and that figure to be a
circle which is not strictly a circle. It is conceived therefore
by the generality of observers, that mathematics is the science
of certainty.

But this is not strictly the case. Mathematics are like those
abstract and imaginary existences about which they are
conversant. They may constitute in themselves, and in the
apprehension of an infallible being, a science of certainty. But
they come to us mixed and incorporated with our imperfections.
Our faculties are limited; and we may be easily deceived, as to
what it is that we see with transparent and unerring clearness,
and what it is that comes to us through a crooked medium,
refracting and distorting the rays of primitive truth. We often
seem clear, when in reality the twilight of undistinguishing
night has crept fast and far upon us. In a train of deductions,
as in the steps of an arithmetical process, an error may have
insinuated itself imperceptibly at a very early stage, rendering
all the subsequent steps a wandering farther and farther from the
unadulterated truth. Human mathematics, so to speak, like the
length of life, are subject to the doctrine of chances.
Mathematics may be the science of certainty to celestial natures,
but not to man.

But, if in the case of pure mathematics, we are exposed to the
chances of error and delusion, it is much worse with mixed
mathematics. The moment we step out of the high region of
abstraction, and apply ourselves to what we call external nature,
we have forfeited that sacred character and immunity, which we
seemed entitled to boast, so long as we remained inclosed in the
sanctuary of unmingled truth. As has already been said, we know
what passes in the theatre of the mind; but we cannot be said
absolutely to know any thing more. In our speculations upon
actual existences we are not only subject to the disadvantages
which arise from the limited nature of our faculties, and the
errors which may insensibly creep upon us in the process. We are
further exposed to the operation of the unevennesses and
irregularities that perpetually occur in external nature, the
imperfection of our senses, and of the instruments we construct
to assist our observations, and the discrepancy which we
frequently detect between the actual nature of the things about
us and our impressions respecting them.

This is obvious, whenever we undertake to apply the processes of
arithmetic to the realities of life. Arithmetic, unsubjected to
the impulses of passion and the accidents of created nature,
holds on its course; but, in the phenomena of the actual world,
"time and chance happeneth to them all."

Thus it is, for example, in the arithmetical and geometrical
ratios, set up in political economy by the celebrated Mr.
Malthus. His numbers will go on smoothly enough, 1, 2, 4, 8, 16,
32, as representing the principle of population among mankind,
and 1, 2, 3, 4, 5, 6, the means of subsistence; but restiff and
uncomplying nature refuses to conform herself to his dicta.

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