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Such a knowledge is quite unnecessary, and therefore View of causes are no more cognisable by our intellectual Bacon's powers than colours by a man born blind; nay, who- Philosophy. ever will be at the pains to consider this matter agreeably to the received rules and maxims of logic, will find that necessary connection, or the bond of causation, can no more be the subject of philosophical discussion by man, than the ultimate nature of truth. It is precisely the same absurdity or incongruity, as to propose to examine light with a microscope. Other rational creatures may perceive them as easily as we hear sounds. All that we can say is, that their existence is probable, but by no means certain. Nay, it may be (and we may never know it) that we are not the efficient causes of our own actions, which may be effected by the Deity or by ministering spirits; and this may even be true in the material world. But all this is indifferent to the real occupation of the philosopher, and does not affect either the certainty, the extent, or the utility of the knowledge which he may acquire.

View of viction, reasons and persuasion, allurements and emoBacon's tions, of gravity, magnetism, irritability, &c.; and we Philosophy carry on conversations on these subjects with much entertainment and seeming instruction. Language is the expression of thought, and every word expresses some notion or conception of the mind; therefore it must be allowed, that we have such notions as are expressed by cause, power, energy. But it is here, as in many cases, we perceive a distinction without being able to express it by a definition; and that we do perceive the relation of causation as distinct from all others, and in particular as distinct from the relation of contiguity in time and place, or the relation of agent, action, and patient, must be concluded from the uniformity of language, which never confounds them except on purpose, and when it is perceived. But even here we shall find, that none of the terms used for expressing those powers of substance which are conceived as the causes of their characteristic phenomena, really express any thing different from the phenomena themselves. Let any person try to define the terms gravity, elasticity, sensibility, and thre like, and he will find that the definition is nothing but a description of the phenomenon itself. The words are all derivatives, most of them verbal derivatives, implying action, gravitation, &c. As the general resemblances in shape, colour, &c. are expressed by the natural historian by generic terms, so the general resemblances in event are expressed by the philosopher in generic propositions, which, in the progress of cultivation, are also abbreviated into generic terms.

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this connection a

ciple.

This abundantly explains the consistency of our language on this subject, both with itself and with the operations of nature, without however affording any argument for the truth of the assumption, that causes are the objects of philosophic research as separate existences; or that this supposed necessary connection is a necessary The per- truth, whether supreme or subordinate. But since the ception of perception of it has its foundation in the constitution of the human mind, it seems intitled to the name of a first first prin- principle. We are hardly allowed to doubt of this, when we consider the importance of it, and the care of nature to secure us in all things essential to our safety and well-being, from all danger, from inattention, ignorance, or indolence, by an instinct infallible in its information, and instantaneous in its decisions." It would not be like her usual care (says Hume), if this operation of the mind, by which we infer like effects from like causes, and vice versa, were entrusted to the fallacious deduction of our reason, which is slow in its operations, appears not in any degree during the first years of infancy, and in every age and period of human life is extremely liable to error. It is more conformable to her ordinary caution (mark the acknowledgement) to secure so necessary an act of the mind by some instinct, or blind tendency, which may be infallible and rapid in all its operations, may discover itself at the first appearance of life, and may be independent of all the laboured deductions of reason. As she has taught us the use of our limbs, without giving us any knowledge of the nerves and muscles by which they are actuated; so she has implanted in us an instinct, which carries forward the thought in a course conformable to that established among external objects, though we be ignorant of the powers and forces on which this regularity depends."

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the disco

We are now able to appreciate the high pretensions The object of the philosopher, and his claim to scientific superiority, of the phiWe now see that this can neither be founded on any sci-losopher entific superiority of his object, nor of his employment. very of His object is not causes; and his discoveries are nothing physical but the discovery of general facts, the discovery of phy-laws. sical laws and his employment is the same with that of the descriptive historian. He observes and describes with care and accuracy the events of nature; and then he groups them into classes, in consequence of resem bling circumstances, detected in the midst of many others which are dissimilar and occasional. By gradually throwing out more circumstances of resemblance, he renders his classes more extensive; and, by carefully marking those circumstances in which the resemblance is observed, he characterises all the different classes: and, by a comparison of these with each other, in respect to the number of resembling circumstances, he distributes his classes according to their generality and subordination; thus exhausting the whole assemblage, and leaving nothing unarranged but accidental varieties. In this procedure it is to be remarked, that every grouping of similar events is, ipso facto, discovering a general fact, a physical law; and the expression of this assemblage is the expression of the physical law. And as every observation of this constancy of fact affords an opportunity for exerting the instinctive inference of natural connection between the related subjects, every such observation is the discovery of a power, property, or quality, of natural substance. And from what has been said, this observation of event is all we know of the connection, all we know of the natural power. And when the philosopher proceeds farther to the arrangement of events, according to their various degrees of complication, he is, ipso facto, making an arrangement of all natural powers according to their various degrees of subordinate influence. And thus his occupation is perfectly similar to that of the descriptive historian, classification and arrangement; and this constitutes all the science attainable by both.

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View of improve art: Or, in compliance with that natural inBacon's stinct so much spoken of, Philosophy is the study of the Philosophy phenomena of the universe, with a view to discover their causes, to explain subordinate phenomena, and to improve art.

46 The employment of the philosopher.

47 Phenomeneology.

The task is undoubtedly difficult, and will exercise our noblest powers. The employment is manly in itself, and the result of it important. It therefore justly merits the appellation of philosophy, although its objects are nowise different from what occupy the attention of other men.

The employment of the philosopher, like that of the natural historian, is threefold; DESCRIPTION, ARRANGEMENT and REFERENCE; while the objects are not things but events.

The description, when employed about events, may be more properly termed history. A philosophical his A philosophical his tory of nature consists in a complete or copious enumeration and narration of facts, properly selected, cleared of all unnecessary or extraneous circumstances, and accurately narrated. This constitutes the materials of philosophy. We cannot give a better example of this branch of philosophical occupation than astronomy.

From the beginning of the Alexandrian school to this day, astronomers have been at immense pains in observing the heavenly bodies, in order to detect their true motions. This has been a work of prodigious difficulty: for the appearances are such as might have been exhibited although the real motions had been extremely different. Not that our senses give us false information; but we form hasty, and frequently false judgments, from these informations; and call those things deceptions of sense, which are in fact errors of judgment. But the true motions have at last been discovered, and have been described with such accuracy, that the history may be considered as nearly complete. This is to be found in the usual systems of astronomy, where the tables contain a most accurate and synoptical account of the motion; so that we can tell with precision in what point of the heavens a planet has been seen at any instant that can be named.

Sir Isaac Newton's Optics is such another perfect model of philosophical history, as far as it goes. This part of philosophy may be called PHENOMENOLOGY.

Having in this manner obtained the materials of philosophical description, we must put them into a compendious and perspicuous form, so that a general knowledge of the universe may be easily acquired and firmly retain ed. This is to be done by classification and arrangement, and this classification must proceed on resemblances observed in the events; and the subsequent arrangement must be regulated by the distinctions of which those resemblances are still susceptible. This assemblage of events into groups must be expressed. They are facts; therefore the expression must be propositions. These propositions must be what the logicians call general or abstract propositions; for they express, not any individual fact of the assemblage, but that circumstance in which they all resemble. Such propositions are the following: Proof is accompanied by belief; kindness is accompanied by gratitude; impulse is accompanied by motion. Investiga. These are usually called general facts; but there are none suck; every fact is individual. This language, however inaccurate, is very safe from misconstruction, and we may use it without scruple. These proposi

tion.

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tions are NATURAL or PHYSICAL LAWS; and then the View of detecting and marking those resemblances in event, is Bacon's the investigation of physical laws; and we may denoPhilosophy minate this employment of the philosopher INVESTIGA

TION.

In the prosecution of this task, it will be found that the similarities of fact are of various extent and thus we shall form physical laws of various extent; and we shall also find that some are subordinate to others; for the resemblance of a number of facts in one circumstance does not hinder a part of them from also resembling in another circumstance: and thus we shall find subordinations of fact in the same way as of quiescent qualities. And it is found here, as in natural history, that our assemblage of resembling events will be the more extensive as the number of resembling circumstances is smaller ; and thus we shall have kingdoms, classes, orders, genera, and species of phenomena, which are expressed by physical laws of all those different ranks.

It has been already observed, that this observation of physical laws is always accompanied by a reference of that uniformity of event to a natural bond of union between the concomitant facts which is conceived by us as the cause of this concomitancy; and therefore this procedure of the philosopher is considered as the discovery of those causes, that is, the discovery of those powers of natural substances which constitute their physical relations, and may justly be called their distinguishing qua lities or properties. This view of the matter gives rise to a new nomenclature and language. We give to those powers generic names, such as sensibility, intelligence, irritability, gravity, elasticity, fluidity, magnetism, &c. These terms, without exception, mark resembling circumstances of event; and no other definition can be given of them but a description of these circumstances. In a few cases which have been the subjects of more painful or refined discussion, we have proceeded farther in this abbreviation of language.

We have framed the verb "to gravitate," and the verbal noun "gravitation," which purely expresses the fact, the phenomenon; but is conceived to express the operation or energy of the cause or natural power. It is of importance to keep in mind this metaphysical remark on these terms; for a want of attention to the pure meaning of the words has frequently occasioned very great mistakes in philosophical science.

We may with propriety call this part of the philosopher's employment AITIOLOGY.

We shall give an instance of its most successful application to the class of events already adduced as an example of philosophic history or phenomenology.

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Aitiology,

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Kepler, a celebrated Prussian astronomer, having maturely considered the phenomena recorded in the tables and observations of his predecessors, discovered, amidst all the varieties of the planetary motions, three circum- Kepler's stances of resemblance, which are now known by the laws an inname of Kepler's laws.

1. All the planets describe ellipses, having the sun in one focus.

2. The elliptic areas described by a planet in the different parts of its orbit, are proportional to the times of description.

3. The squares of the periodic times are proportional to the cubes of the mean distances from the

sun.

stance.

:

View of By this observation or discovery, the study of the plaBacon's netary motions were greatly promoted, and the calculaPhilosophy. tion of their appearances was now made with a facility and an accuracy which surpassed all hopes for the calculation of the place of a planet at any proposed instant was reduced to the geometrical problem of cutting off an area from an ellipse of known dimensions, which should bear the same proportion to the whole area, as the time for whose duration the motion is required, has to the known time of a complete revolution.

51 Compre

Long after this discovery of Kepler, Sir Isaac Newton found that these laws of Kepler were only particular cases of a fact or law still more general. He found that 4ended un- the deflections of the planets from uniform rectilineal motion were all directed to the sun; and that the simulmore gene taneous deflections were inversely proportional to the ral law, squares of the distances from that body.

der one

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called gravitation.

Thus was established a physical law of vast extent: but further observation showed him, that the motion of every body of the solar system was compounded of an original motion of projection, combined with a deflection towards every other body; and that the simultaneous deflections were proportional to the quantity of matter in the body towards which they were directed, and to the reciprocal of the square of the distance from it. Thus was the law made still more general. He did not stop here. He compared the deflection of the moon in her orbit with the simultaneous deflection of a stone thrown from the hand, and describing a parabola; and he found that they followed the same law, that is, that the deflection of the moon in a second, was to that of the stone in the same time, as the square of the stone's distance from the centre of the earth, to the square of the moon's distance from it. Hence he concluded, that the deflection of a stone from a straight line was just a particular instance of the deflections which took place through the whole solar system.

The deflection of a stone is one of the indications it gives of its being gravis or heavy; whence he calls it gravitation. He therefore expresses the physical law which obtains through the whole solar system, by saying that "every body gravitates to every other body; and the gravitations are proportional to the quantity of matter in that other body, and inversely proportional to the square of the distance from it."

Thus we see how the arrangement of the celestial phenomena terminated in the discovery of physical laws; and that the expression of this arrangement is the law itself.

Since the fall of a heavy body is one instance of the physical law, and since this fall is considered by all as the effect of its weight, and this weight is considered as the cause of the fall, the same cause is assigned for all the deflections observed in the solar system; and all the matter in it is found to be under the influence of this cause, or to be heavy: and thus his doctrine has been denominated the system of universal gravitation.

Philosophers have gone farther, and have supposed that gravity is a power, property, or quality, residing in all the bodies of the solar system. Sir Isaac Newton does not expressly say so, at least in that work where he gives an account of these discoveries. He contents himself with the immediate consequence of the first axiom in natural philosophy, viz. that every body remains in a state of rest, or of uniform rectilineal motion, unless afVOL. XVI. Part I.

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this law

fected by some moving force. Since the bodies of the. View of solar system are neither in a state of rest, nor of uni- Bacon's form rectilineal motion, they must be considered as so Philosophy. affected; that is, that there operates on every one of them a moving force, directed towards all the others, and having the proportions observed in the deflection. 53 Other philosophers have endeavoured to show, that Attempts this general fact, detected by Sir Isaac Newton, is in- to include cluded in another still more general, viz. that every bo- under imdy moves which is impelled by another body in motion. pulse, They assert, that all the bodies of the solar system are continually impelled by a fluid which they call ether, which is moving in all places, and in all directions, or in circular vortices, and hurries along with it the planets and all heavy bodies. It would seem that the familiarity of motion produced by impulse, at least in those instances in which our own exertions are most employed, has induced philosophers to adopt such notions; perhaps, too, they are influenced by an obscure and indistinct notion affixed to the term action, as applied to changes in the material world, and which has given rise to an axiom," that a body cannot act at a distance, or where it is not ;" and thus have thought themselves obliged to look out for an immediate and contiguous agent in all those phenomena.

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But the philosophers who profess to be most scrupulous in their adherence to the rules of philosophic discussion, deny the legitimacy of this pretended investigation of causes, saying that this doctrine is in direct opposition to the procedure of the mind in acquiring the knowledge of causes. Since the fact of impulse is not really observed in the celestial deflections, nor in the motions whilst imof heavy bodies, the law cannot be inferred. They say pulse itself is never obthat it is not even necessary to show that the phenomena served. of the celestial motions are unlike the phenomena of impulse, although this can be done in the completest manner. It is enough that neither the fluid nor the impulse are observed; and therefore they are in the right when they assert, that there is inherent in, or accompanies all the bodies of the system, a power by which they deflect to one another. See OPTICS.

The debate is foreign to our present purpose, which is only to show how the observation and arrangement of phenomena terminates in the discovery of their causes, or the discovery of the powers or properties of natural substances.

This is a task of great difficulty, as it is of great importance. There are two chief causes of this difficulty.

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vestigation.

1. In most of the spontaneous phenomena of nature there is a complication of many events, and some of them escape our observation. Attending only to the most obvious or remarkable, we conjoin these only in our imagination, and are apt to think these the concomitant Causes of events in nature, the proper indication of the cause, and the difficul the subjects of this philosophical relation, and to suppose ty of philothat they are always conjoined by nature. Thus it was sophical inthought that there resided in a vibrating chord a by which the sensation of sound was excited, or that a chord had a sounding quality. But it appears clearly from observation that there is an inconceivable number of events interposed between the vibration of the chord and the sensitive affection of our ear; and therefore, that sound is not the effect of the vibration of the chord, but of the very last event of this series: and this is com3 C pletely

View of pletely demonstrated by showing that the vibration and Bacon's the sound are not necessarily connected, because they are Philosophy; not always connected, but require the interposition of air or of some other elastic body.

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Means of

insuring

success,

These observations show the necessity of the most accurate and minute observation of the phenomena, that none of those intermediate events may escape us, and we be thus exposed to the chance of imaginary connections between events which are really far asunder in the procedure of nature. As the study has improved, mistakes of this kind have been corrected; and philosophers are careful to make their trains of events under one name as short as possible. Thus, in medicine, a drug is no longer considered as a specific remedy for the disease which is sometimes cured when it has been used, but is denominated by its most immediate operation on the animal frame it is no longer called a febrifuge, but a sudorific.

2. When many natural powers combine their infinence in a spontaneous phenomenon of nature, it is frequently very difficult to discover what part of the complicated effect is the effect of each; and to state those circumstances of similarity which are the foundation of a physical law, or entitle us to infer the agency of any natural power. The most likely method for insuring success in such cases is to get rid of this complication of event, by putting the subject into such a situation that the operation of all the known powers of nature shall be suspended, or so modified as we may perfectly understand their effects. We can thus appreciate the effects of such as we could neither modify nor suspend, or we can discover the existence of a new law, the operation of a

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is a matter of fact, a physical law of human thought, explained. that one simple, clear, and unequivocal experiment,

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Theory or

mena,

gives us the most complete confidence in the truth of a general conclusion from it to every similar case. Whence this anomaly? It is not an anomaly or contradiction of the general maxim of philosophical investigation, but the most refined application of it. There is no law more general than this, that "Nature is constant in all her operations." The judicious and simple form of our experiment insures se (we imagine) in the complete knowledge of all the circumstances of the event. Upon this supposition, and this alone, we consider the experiment as the faithful representative of every possible case of the conjunction. This will be more minutely considered afterwards.

The last branch of philosophic occupation is the exexplanation planation of subordinate phenomena. This is nothing of subordimore than the referring any particular phenomenon to nate phenothat class in which it is included; or, in the language of philosophy, it is the pointing out the general law, or that general fact of which the phenomenon is a particular instance. Thus the feeling of the obligations of virtue is thought to be explained, when it is shown to be a

particular case of that regard which every person has for View of his dearest interests. The rise of water in pumps is ex- Bacon's plained, when we show it to be a particular case of the Philosophy. pressure of fluids, or of the air. The general law under which we show it to be properly arranged is called the PRINCIPLE of the explanation, and the explanation itself is called the THEORY of the phenomenon. Thus Euler's explanation of the lunar irregularities is called a theory of the lunar motions on the principle of gravita

tion.

This may be done either in order to advance our own knowledge of nature, or to communicate it to others. If done with the first view, we must examine the phenomenon minutely, and endeavour to detect every circumstance in it, and thus discover all the known laws of nature which concur in its production; we then appreciate the operation of each according to the circumstances of its exertion; we then combine all these, and compare the result with the phenomenon. If they are similar, we have explained the phenomenon. We cannot give a better example than Franklin's explanation of the phenomena of thunder and lightning. See LIGHTNING, and ELECTRICITY Index.

If we explain a phenomenon from known principles, we proceed synthetically from the general law already established and known to exert its influence in the present instance. We state this influence both in kind and degree according to the circumstances of the case; and having combined them, we compare the result with the phenomenon, and show their agreement, and thus it is explained. Thus, because all the bodies of the solar system mutually gravitate, the moon gravitates to the sun as well as to the earth, and is continually, and in a certain determinate manner, deflected from that part which she would describe did she gravitate only to the earth. Her motion round the earth will be retarded during the first and third quarters of her orbit, and accelerated during the second and fourth. Her orbit and her period will be increased during our winter, and diminished during our summer. Her apogee will advance, and her nodes will recede; and the inclination of her orbit will be greatest when the nodes are in syzigee, and least whea they are in quadrature. And all these variations will be in certain precise degrees. Then we show that all these things actually obtain the lunar motions, and they are considered as explained.

This summary account of the object and employment in all philosophical discussion is sufficient for pointing out its place in the circle of the sciences, and will serve tə direct us to the proper methods of prosecuting it with success. Events are its object; and they are considered as connected with each other by causation, which may therefore be called the philosophical relation of things. The following may be adopted as the fundamental proposition on which all philosophical discussion proceeds, and under which every philosophical discussion or discovery may be arranged:

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Every change that we observe in the state or condi-Fundamen tion of things IS CONSIDERED BY US as an effect, indi tal proposicating the agency, characterising the kind, and deter-tion of phi mining the degree of its INFERRED cause."

As thus enounced, this proposition is evidently a phy-" sical law of human thought. It may be enounced as a necessary and independent truth, by saying, every change in the state and condition of things IS AN EFFECT, &c.

losophical discussion

Bacon's

* Essays

on the In

tellectual Powers of

Man.

60

View of And accordingly it has been so enounced by Dr Reid* ; We believe that Mr Hume is the first author who View of and its title to this denomination has been abundantly has ventured to call the truth of this opinion in question; Bacon's Philosophy. supported by him. But we have no occasion to consi- and even he does it only in the way of mere possibility. Philosophy. der it as possessing this quality. We are speaking of speaking of He acknowledges the generality of the opinion; and he philosophy, which is something contingent, depending only objects to the foundation of this generality and Controon the existence and constitution of an intellectual he objects to it merely because it does not quadrate with verted by being such as man; and, in conformity to the view his theory of belief; and therefore it may happen that Mr Hume which we have endeavoured to give of human knowledge some men may have no such opinion. But it must be in the subjects of philosophical relation, it is quite suf- observed on this occasion, that the opinion of a philosoficient for our purpose that we maintain its title to the pher is of no greater weight in a case like this than that rank of an universal law of human thought. This will of a ploughboy. If it be a first principle, directing the make it a first principle, even although it may not be a opinions and actions of all, it must operate on the minds necessary truth. of all. The philosopher is the only person who may chance to be without it: for it requires much labour, and long habits resolutely maintained, to warp our natural sentiments; and experience shows us that they may be warped if we are at sufficient pains. It is also worthy of remark, that this philosopher seems as much under the influence of this law as ordinary mortals. It is only when he is aware of its not tallying with his other doctrines that his scruples appear. Observe how with great he speaks when off his guard: "As to those impres- inconsistsions which arise from the senses, their ultimate cause' ency. is, in my opinion, perfectly inexplicable by human reason; and it will always be impossible to decide with certainty whether they arise immediately from the object, are produced by the creative power of the mind, or are derived from the Author of our being."

All the proof necessary for this purpose is universa-
lity of fact; and we believe this to be without excep-
tion. We are not to expect that all mankind have made,
or will ever make, a formal declaration of their opinion;
but we may venture to say that all have made it, and
continually do make it, virtually. What have the phi-
losophers of all ages been employed about but the disco-
very of the causes of those changes that are incessantly
going on? Nil turpius physico (says Cicero) quam fieri
sine causa quidquam dicere. Human curiosity has been
directed to nothing so powerfully and so constantly as to
this. Many absurd causes have been assigned for the
phenomena of the universe; but no set of men have
ever said that they happened without a cause. This is
so repugnant to all our propensities and instincts, that
even the atheistical sect, who, of all others, would have
profited most by the doctrine, have never thought of
advancing it. To avoid so shocking an absurdity, they
have rather allowed that chance, that the concourse of
atoms, are the causes of the beautiful arrangements of
nature. The thoughtless vulgar are no less solicitous
than the philosophers to discover the cause of things;
and the poet expresses the natural and instinctive pas-
sion of all men, when he says,

Felix qui potuit rerum cognoscere causas.
And this anxiety is not to nourish, but to get rid of su-
perstitious fears: for thus

:

you

metus omnes, ei inexorabile fatum
Subjecit pedibus, strepitumque Acherontis avari.
Had men never speculated, their conduct alone gives
sufficient evidence of the universality of the opinion.
The whole conduct of man is regulated by it, nay, al-
most wholly proceeds upon it, in the most important
matters, and where experience seems to leave us in
doubt and to act otherwise, as if any thing whatever
happened without a cause, would be a declaration of in-
sanity. Dr Reid has beautifully illustrated this truth,
by observing, that even a child will laugh at you
if
try to persuade him that the top, which he misses from
the place where he left it, was taken away by nobody.
You may persuade him that it was taken away by a
fairy or a spirit; but he believes no more about this no-
body, than the master of the house when he is told that
nobody was the author of any piece of theft or mischief.
What opinion would be formed, says Dr Reid, of the
intellects of the juryman, on a trial for murder by per-
sons unknown, who should say that the fractured skull,
the watch and money gone, and other like circum-
stances, might possibly have no cause? he would be
pronounced insane or corrupted.

Among these alternatives he never thought of their not being derived from any cause.

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But it is not enough to show that this is a physical law of the human mind: we have assumed it as a first principle, the foundation of a whole science; therefore not included in or derived from any thing more general. Mr Hume's endeavours to prove that it is not a necessary truth, show with sufficient evidence that most attempts to derive it in the way of argument are petitiones principii; a thing very commonly met with in all attempts to prove first principles. It cannot be proyed This proby induction of facts that every event has a cause, be- position a first princause induction always supposes an observed fact or ciple incaevent. Now in by far the greatest number of events pable of the causes are unknown. Perhaps in no event what-proof. ever do we know the real cause, or that power or energy which, without any intervention, produces the effect. No man can say, that in the simplest event which he ever observed, he was fully apprised of every circumstance which concurred to its production. We suppose that no event in nature can be adduced more simple than the motion of a suspended glass ball when gently struck by another glass ball; and we imagine that most of our readers will say that he perfectly sees every thing which happens in this phenomenon. We believe, too, that most of our readers are of opinion that a body is never put in motion but by the impulse of another, except in the cases of animal motion; and that they are disposed to imagine that magnets put iron in motion, and that an electrified body moves another, by means of an interposed though invisible fluid somehow circulating round them. Now we must inform such readers, that unless the stroke has been very smart, so smart indeed as to shatter the glass balls, the motion of the suspended ball was produced without impulse: that is, the two balls were not in contact during the stroke; and the distance between them was not less than the 3 C 2 9000th

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