Thomas Reid.

The works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters online

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power, because the common sense of man-
kind dictates, that what a man did volun-
tarily and with intention, he had power not
to do:

2. A second reason of my dissent is,
That the guilt of a bad action is diminished
in proportion as it is more difficult to resist
the motive. Suppose a man entrusted with
a secret, the betraying of which to the ene-
my may ruin an army. If he discloses it
for a bribe, however great, he is a villain
and a traitor, and deserves a thousand
deaths. But, if he falls into the enemy's
hands, and the secret be wrested from him
by the rack, our sentiments are greatly
changed; we do not charge him with vil-
lany, but with weakness. We hardly at all
blame a woman in such a case, because we
conceive torture, or the fear of present
death, to be a motive hardly resistible by
the weaker sex. p-

As it is, ^hereforejthe uniform judgment
of mankind! that, where the deed is the
same, andCTie will and intention the same,
the degree of guilt must depend upon the
difficulty of resisting the motive, will it not
follow, that, when the motive is absolutely
irresistible, the guilt vanishes altogether ?

3. That this is the common sense of
mankind, appears further from the way in
which we treat madmen. They have will
and intention in what they do ; and, there-
fore, if no more is necessary to constitute a
crime, they ought to be found guilty of
crimes. Yet no man conceives that they
can be at all subjects of criminal law. For
what reason ? for this, in my opinion, that
they have not that power of self-command
which is necessary to make a man account-
able for his conduct.

You suppose, my Lord, a physical power
to forbear an action even when it is neces-
sary. But this I cannot grant. Indeed,
upon the system of free agency, I can easily
conceive a power which is not exerted ; but,
upon the system of necessity, there can be
no such thing— every power that acts by
necessity must be exerted.

I do indeed think, that a man may act
without a motive ; and that, when the mo-
tives to action lie all on one side, he m.iy
act in contradiction to them. But I agree
with your Lordship, that all such actions
are capricious ; and I apprehend that, if
there were no actions of this kind, there
could be no such thing as caprice, nor any
word in language to signify it : for why
should every language have a word to sig-
nify a thing which never did nor can exist ?

I agree also with your Lordship, that
there can be no merit in such an action,
even if it is innocent. But if it is vicious,
it has the highest degree of demerit ; for it
it is sinning without any temptation, and
serving the devil without any wages. It
ought to be observed, however, that a vir-
tuous action can never becapricious; because
there is always a just and sufficient motive
to it. For, if I have no other mptive, I
must at least have this, that is a worthy
action, and is my duty ; which, in reason,
ought to weigh down all motives that cai
be put into the opposite scale. A capricious
action may be innocent, and then it is
folly ; or it may be vicious, and then it is
pure wickedness.

Liberty, like all other good gifts of God,
may be abused. As civil liberty may be
abused to licentiousness, so our natural
liberty may be abused to caprice, folly, and
vice. But the proper exercise of liberty is,
after weighing duly the motives on both sides,
to be determined, not by the strongest mo-
tive, but by that which has most authority.

It is of great importance in this matter,
to distinguish between the authority of mo-
tives and their force. The part that is
decent, that is manly, that is virtuous, that
is noble, has always authority upon its side.
Every man feels this authority in his own
breast ; and there are few men so wicked
as not to yield to it when it has no antago-

E 2


But pleasure, interest, passion, sloth,
often muster a great force on the other side,
which, though it has no authority, has often
the greater power; and a, conflict arises
between these opposite parties. Every
man is conscious of this conflict in his own
breast, and is too often carried down by the
superior force of the party which he knows
to have no authority.

This is the conflict which Plato describes
between reason and appetite ; this is the
conflict which the New Testament describes
between the spirit and the flesh. The op-
posite parties, like Israel and Amalek, dis-
pute the victory in the plain. When the
self-determining power, like Moses upon
the mount, lifts up its hand and exerts
itself, then Israel prevails, and virtue is
triumphant ; but when its hands hang down
and its vigour flags, then Amalek prevails.
I am, my dear Lord, most respectfully yours,
Tho. Reid.



r : 17 . 73 -

Dr Priestley, in his last
book, thinks that the power of perception,
as well as all the other powers that are
termed mental, is the result of such an
organical structure as that of the brain.
Consequently, says he, the whole man
becomes extinct at death, and we have no
hope of surviving the grave, but what is
derived fiom the light of Revelation. I
would be glad to know your Lordship's
opinion, whether, when ray brain has lost
its original structure, and when, some hun-
dred years after, the same materials are
again fabricated so curiously as to become
an intelligent being, whether, I say, that
being will be mc ;' or, if two or three such
beings should be formed out of my brain,
whether they will all be me, and conse-
quently all be one and the same intelligent

This seems to me a great mystery, hut
Priestley denies all mysteries. He thinks,
and rejoices in thinking so, that plants
have some degree of sensation. As to the
lower animals, they differ from us in degree
only, and not in kind. Only they have no
promise of a resurrection. If this be true,
why should not the King's advocate be
ordered to prosecute criminal b> riles, and

" Our Engliih / being of an ambiguous sound, it
would he convenient in psychology, could we occasion-
ally employ me for a nominative, as the French do
their moi But this nnt being the ease, Reid is here,
a6 elsewhere in his letters, grammatically at fault.

you criminal judges to try them ? You are
obliged to Dr Priestley for teaching you
one-half of your duty, of which you knew
nothing before. But I forgot that the
fault lies in the legislature, which has not
givenyoulawsforthispurpose. I hope,how-
ever,when anyof them shall be brought to a
trial, that he will be allowed a. jury of his peers.
I am not much surprised that your
Lordship has found little entertainment in
a late French writer on human nature.*
From what I learn, they are all become
rank Epicureans. One would think that
French politesse might consort very well
with disinterested benevolence ; but, if we
believe themselves, it is all grimace. It is
flattery, in order to be flattered ; like that
of the horse, who when his neck itches,
scratches his neighbour, that he may be
scratched by him again. I detest all sys-
tems that depreciate human nature. If it
be a delusion, that there is something in
the constitution of man that is venerable
and worthy of its author, let me live and
die in that delusion, rather than have my
eyes opened to see my species in a humi-
liating and disgusting light. Every good
man feels his indignation rise against those
who disparage his kindred or his country ;
why should it not rise against those who
disparage his kind ? Were it not that we
sometimes see extremes meet, I should
think it very strange to see atheists and
high-shod divines contending as it were
who should most blacken and degrade human
nature. Yet I think the atheist acts the
more consistent part of the two : for surely
such views of human nature tend more to
promote atheism, than to promote religion
and virtue. .....



October 1, 1775.
The theory of agriculture is
a wide and deep ocean, wherein we soon go
beyond our depth.

I believe a lump of dry clay has much
the same degree of hardness, whether the
weather be hot or cold. It seems to be
more affected by moisture or drought : and
to be harder in dry weather, and more
easily broken when a little moistened. But
there is a degree of wetness in clay which
makes it not break at all when struck or
pressed ; it is compressed and changes its
figure, but does not break.

Cla y grou nd, I think, ought to be ploughed

• Helvetius, De I'Esprit — Loan WoomioiisELBB.
Hardly; this work I'einf then, nearly twenty year
old. Probably the work, " Sur.l Uommo."_H.



in the middle state between wetness and
dryness, for this reason : When too dry,
the plough cannot enter, or cannot make
handsome work. Those clods are torn
up, which require great labour and ex-
pense to break them. And unless they
are broken, the roots of vegetables cannot
enter into them. When too wet, the fur-
row, in being raised and laid over by the
plough, is very much compulsed, but not
broken. The compression makes it much
harder when it dries, than it would have
been without that compression. But when
the ground is neither too wet nor too dry,
the farrow, in being raised and laid over
by the plough, breaks or cracks with in-
numerable crevices, which admit air and
moisture, and the roots of vegetables.

Clay, when exposed in small parts to
the air, and to alternate moisture and
drought, mellows into mould. Thus a clod
of clay, which is so hard in seed-time that
you may stand upon it without breaking it,
will be found in autumn of the colour of
mould, and so softened, that when you
press it with the foot it crumbles to pieces.
On some clays this change is produced in a
shorter time, in the same circumstances ;
others are more refractory, and require
more time.

If wet clay is put into the fire uncom-
pressed, I am informed that it burns to
ashes, which make no bad manure.

But if the clay be wrought and compressed

when wet, and then dried, and then put

into the fire, it burns into brick, and with

a greater degree of heat, into a kind of


I These, my Lord, are facts ; but to deduce
\ them from principles of attraction and re-
pulsion, is beyond the reach of my philo-
sophy : and I suspect there are many things
in agriculture, and many things in che-
mistry, that cannot be reduced to such
principles ; though Sir Isaac Newton seems
to have thought otherwise.

Human knowledge is like the steps of a
ladder. The first step consists of particular
truths, discovered by observation or expe-
riment : the second collects these into more
general truths : the third into still more
general- But there are many such steps
before we come to the top ; that is, to the
most general truths. Ambitious of know-
ledge, and unconscious of our own weak-
ness, we would fain jump at once from the
lowest step to the highest ; but the conse-
quence of this is, that we tumble down,
and find that our labour must be begun
anew. Is not this a good picture of a phi-
losopher, my Lord ? I think so truly ; and
I should be vain of it, if I were not afraid
that I have stolon it from Lord Bacon.
| I am, &c.
( Tho. Rkid.



JVo date — but supposed 1775-
My Lord, — I have some compunction for
having been so tardy in answering the letter
which your Lordship dtd me the honour to
write me of the 6th November, especially
as it suggests two very curious subjects of
correspondence. But, indeed, my vacant
time has been so much filled up with trifles
of College business, and with the frequent
calls of a more numerous class of students
than I ever had before, that there was no
room for anything that could admit of

Y ou have expressed with great elegance
and strength the conjecture I hinted with
regard to the generation of plants.

I am indeed apt to conjecture, that both
plants and animals are at first organized
atoms, having all the parts of the animal
or plant, but so slender, and folded up in
such a manner, as to be reduced to a par-
ticle far beyond the reach of our senses, and
perhaps as small as the constituent parts
of water.* The earth, the water, and the
air may, for anything I know, be full of
such organized atoms. They may be no
more liable to hurt or injury, than the con-
stituent elementary parts of water or air.
They may serve the purposes of common
matter until they are brought into that
situation which nature has provided for
their unfolding themselves. When brought
into their proper matrix or womb, perhaps
after some previous preparations, they are
commonly surrounded with some fluid
matter, in which they unfold and stretch
themselves out to a length and breadth
perhaps some thousand times greater than
they had when folded up in the atom.
They would now be visible to the naked
eye, were it not that their limbs and vessels
are so slender that they cannot be distin-
guished from the fluid in which they float.
All is equally transparent, and therefore
neither figure nor colour can be discerned,
although the object has a considerable bulk.
The foetus now has a fluid circulating in its
vessels ; all the animal functions go on ; it
is nourished and grows ; and some parts,
first the heart, then the head, then the

* This o- inion is sim lar to that ol M. Bonnet.
Sec his " Considi rations sur les Corps Organizes,"
and his " Contemplation de la Nature." J ord
Woomiou rlee. — Rcid's opinion has comparatively
little resemblance to the involution theory of Bonnet :
it bears, however, a strong analogy to the Pansper-
mia of the Ionic philosophers, more especially as
I medified by some of the recent physiological specu-
latists of Germany This conjecture is curious, as
a solitary escapade of our cautious philosopher iu
the region of imagination.— H,



opine, by getting some colour, become

It is to be observed, that, from the time
that the heart first appears in the pellucid
liquor, until the time of birth, the animal
grows gradually and insensibly, as it does
after birth. But, before it is visible, it must
have increased in size many thousand times
in a few days. This does not look like
growth by nourishment, but like a sudden
unfolding of parts, which before were
wrapped up in a small atom.

I go along with your Lordship cordially,
till you come to the first formation of an
organized body. But there I hesitate.
"May there," say you, " not be particles
of a certain kind endowed with a power to
form in conjunction an organized body V
Would your Lordship allow that certain
letters might be endowed with the power
of forming themselves into an " Iliad" or
'' ^Eneid," or even into a sensible discourse
in prose ?* I confess our faculties carry
us but a very little way in determining
what is possible and what is impossible,
and therefore we ought to be modest. But
I cannot help thinking that such a work
as the " Iliad," aud much more an animal
or vegetable body, must have been made by
express design and counsel employed for
that end. And an author whom I very
much respect has taught me, " That we
form this conclusion, not by any process of
reasoning, but by mere perception and feel-
ing."^ And I think that conclusions formed
in this manner, are of all others most to
be trusted. It seems to me as easy to con-
trive a machine that should compose a
variety of epic poems and tragedies, as to
contrive laws of motion, by which unthink-
ing particles of matter should coalesce into
a variety of organized bodies.

" But," says your Lordship, " certainly
the Almighty has made none of his works
so imperfect as to stand in need of perpe-
tual miracles." Can we, my Lord, shew,
by any good reason, that the Almighty
finished his work at a stroke, and has con-
tinued ever since an unactive spectator ?
Can we prove that this method is the best ;
or that it is possible that the universe should
be well governed in this way ? I fear we

And, if his continued operation be neces-
sary or proper, it is no miracle, while it
is uniform, and according to fixed laws.
Though we should suppose the gravitation
of matter to be the immediate operation of
the Deity, it would be no miracle, while it
is constant and uniform ; but if in that case
it should cease for a moment, only by his

* This illustration is borrowed from Cicero. <" De
.•Jatura Deoium." 1. li c. 37.)— H

+ Lord Karnes himself. " Fssays on Morality,"
ac; t> Chapter < l On the Mea of Power."

withholding his hand, this would be a mi-

That an animal or vegetable body is a
work of art, and requires a skilful workman,
I think we may conclude, without going
beyond our sphere. But when we would
determine how it is formed, we have no
data; and our most rational conjectures are
only reveries, and probably wide of the
mark. We travel back to the first origin
of things on the wings of fancy. We would
discover Nature in puris naturalibus, and
trace her first operations and gradual pro-
gress. But, alas ! we soon find ourselves
unequal to the task : and perhaps this is
an entertainment reserved for us in a future

As to what you say about earth or soil ;
there seems, indeed, to be a repulsion of the
parts, when it is enriched by the air, or by
manure. And, in consequence of this, it
swells and occupies more space. But, I
conceive, it gets an additional quantity of
matter, from the moisture and air which it
imbibes, and thereby increases both in bulk
and weight. I have been told that a dung-
hill made up of earth, dung, and lime,
trenched over two or three times, at proper
intervals, and then led out, will be found
to make more cart-loads than it received :
and I believe this to be true. If the earth
taken out of a pit does not fill it again, I
am apt to think there must have been va-
cuities in the earth at first, perhaps made
by the roots of plants that have decayed,
by moles, insects, or other causes. — I am,
my Lord, <\e.

Tho. Reid.



Glasgow College, Mag 19, 1780.

My Lord, — In order to understand the
preliminary part of Newton's Prmcipia., it
is necessary to attend to his general design,
both in his axioms and definitions.

First, As to his axioms : he sets down the
three laws of motion as axioms. But he
does not mean by this, that they are to be
held as self-evident truths ; nor does he in-
tend to prove them in what he says upon
them. They are incapable of demonstra-
tion, being matters of fact, which universally
obtain in the material world, and which had
before been observed by philosophers, and
verified by thousands of experiments by
Galileo, by Wren, Wallis, Huygens, and
Mariotte, to whom he refers for the proof
of them. Therefore, that he might not
aclumagcre,he lays them down as established
truths, saying some things upon them by


way of illustration, and deducing some gene-
ral corollaries from them.

That this was his view, he expressly says
in the scholium following the axioms :
Jlacteniis principia tradidi, a Mathematics
recepta, et multiplied enpperientia confirmata,
$c. The very same method he follows in
his optics, laying down as axioms what had
before been discovered in that science.

The axioms, or established principles in
the Principia, are three : — \u, Every body
perseveres in its present state, whether of
motion or rest, until it is made to change
that state by some force impressed upon it.
2d, The change of motion produced is al-
ways proportional to the force impressed,
and in the direction of that force. 3-/, All
action of bodies upon each other is mutual
or reciprocal, and in contrary directions ;
that is, if the body A produces any motion
or change of motion in B ; by the reaction
of B, an equal change of motion, but in a
contrary direction, will be produced in A.
This holds in all action of bodies on .each
other, whether by a stroke, by pressure, by
attraction, or by repulsion.

Perhaps, you will say these principles
ought not to be taken for granted, but to
lie proved. True, my Lord, they ought to
be proved by a very copious induction of
experiments ; and, if they are not proved,
the whole system of the Principia falls to
the ground ; for it is all built upon them.
But Sir Isaac thought they were already
proved, and refers you to the authors by
whom. He never intended to prove them,
but to build upon them, as mathematicians
do upon the Elements of Euclid.

Secondly, As to the definitions. They
are intended to give accuracy and precision
to the terms he uses, in reasoning from, the
laws of motion. The definitions are accom-
modated to the laws of motion, and fitted so
as to express with precision all reasoning
grounded upon the laws of motion. And,
for this reason, even the definitions will
appear obscure, if one has not a distinct
conception of the laws of motion always be-
fore his eye.

Taking for granted the laws of motion,
therefore, he gives of vis insita, or
vis inertite, to that property of bodies,
whereby, according to the first and second
laws of motion, they persevere in their
state, and resist any change, either from
rest to motion, or from motion to rest,
or from one degree or direction of motion
to another.

This vis insita is exercised in every case
wherein one body is made to change its
state by the action of another body ; and
the exertion of it may, in different respects,
be called both resistance and impetus.

The reluctance which the body A has to
change its state, which can be overcome

only by a force proportioned to that reluct-
ance, is resistance. The reaction of the
body A upon B, which, according to tl e
third law of motion, is equal to the action 01
B upon A, and in a contrary direction, is

Thus, in every change made in the state
of one body by another, there is mutual
resistance and mutual impetus. The one
never exists without the other. A body at
rest not only resists, but gives an impetus to
the body that strikes it. And a body in
motion coming against a body at rest, not
only gives an impetus to the body that was
at rest, but resists that change of its own
motion which is produced by the stroke.
Each gives an impetus to the other, and
exerts a resistance to the impetus it receives
from the other.

This is the notion which Newton affixes
to the words — impetus and resistance ; and,
I think, it corresponds perfectly with the
third law of motion, but may appear dark if
that is not kept in view.

But, because this notion of resistance and
impetus differs somewhat from the vulgar
application of those words, in order to point
out the difference, he contrasts it with the
vulgar meaning in the words which your
Lordship quotes : — Valgus resistentiam
quiescentibus et impel um mm-entibnstribuiU
sed motus et quirs, ut vulgo concipiuntur,
respectu solo distingunntur, neque semper
verequiescunt qucevulgo tanquam quiescenlia
spectantur. He considers both resistance
and impetus as belonging to every body, in
every case in which it is made to change its
state, whether from rest to motion, or from
motion to rest. It resists the change of its
own state, and, by its reaction, gives an
impetus to the body that acts upon it. The
vulgar, having no notion, or no distinct
notion, of this reaction established by the
third law of motion, suit their language to
their conceptions. He suits his to the laws
of motion.

A post, you say, resists, but has no im-
petus. This is true in the vulgar sense of
the word. But, in order to shew you that
his sense differs somewhat from the vulgar,
he would say, that the post has impetus in
his seuse. And by this he means only, that
the post stops, or changes the motion of the
body that strikes it ; and, in producing this
change, exerts a force equal to that with
which it was struck, but in a contrary
direction. This is a necessary consequence
of the third law of motion. The vulgar
both speak and judge of motion and rest in
a body, by its situation with respect to some
other body, which, perhaps, from prejudice,
they conceive to be at rest. This makes
Newton say, " That motion and rest, as
commonly conceived, are distinguished by
t elation ; nor are those bodies always really



at rest wliicli are commonly conceived to
be at rest-"

Rest, when we speak of bodies, is opposed,

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 14 of 114)