Chapter II (1)

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THE SCIENTIFIC BASIS OF MENTAL AND MORAL PROGRESS.[12]

It is not highly necessary after what has been already said in these pages, to adduce much evidence to show that scientific discoveries, either directly or through the medium of the inventions based upon them, have been a great cause of mental and moral progress. As however there are many persons who do not perceive the dependence of such progress, and especially of moral advance, upon science, a few of the chief relations of those subjects to each other may be pointed out.

The dependence of mental progress upon science may be rendered manifest in several ways:--1st. By showing that new scientific knowledge is continually extending and modifying our views of existing things. 2nd. That inventions based upon scientific discoveries have aided and extended our mental powers:--3rd. That mental phenomena may be made the subject of experiment, observation, analysis, and {84} inference:--4th. That the criteria of truth, and the mental powers and processes employed for discovering and detecting truth, are the same in mental as in physical science, and, 5th. That mental action is subject to the great principles and laws of science. And moral progress may be proved to have a scientific basis:--1st. By shewing that moral actions are a class of mental actions, and therefore subject to the same fundamental laws and influences:--2nd. That the discovery of new scientific knowledge, and the use of inventions based upon it, often conduce to morality:--3rd. That moral phenomena may be made the subject of experiment, observation, analysis, and inference:--4th. That the criteria of truth, and the mental faculties and processes employed, in discovering truth, are the same in moral as in physical science:--5th. That the fundamental rules of morality are subject to the great principles of science:--6th. That moral improvement follows in the wake of scientific advance:--and 7th. By showing the moral influence of experimental research in imparting "the scientific spirit;" promoting a love of truth; dispelling ignorance and superstition; detecting error; imparting certainty and accuracy to our knowledge; inculcating obedience to law; producing uniformity of belief; aiding economy and cleanliness, promoting humanity, &c, &c. Each of these will be treated with extreme brevity.

MENTAL PROGRESS.

The chief object of this chapter is only to shew {85} that mental action is largely consistent with the great principles of science; not that in our present state of knowledge, mental phenomena can be entirely explained by them, or that mental actions involve nothing more than physical and chemical processes.

That mental progress is advanced by scientific discovery is a common circumstance. Our ideas of facts, our knowledge of general principles, our views of man, of nature, and of the Universe; and even our modes of thought, have been gradually and profoundly changed by the new knowledge acquired by means of scientific research. This truth is capable of being most extensively illustrated by a multitude of facts in the whole of the sciences, and in the arts, manufactures, and other subjects dependent upon science. For example, in astronomy, great changes, produced by the results of scientific discovery have taken place in our ideas respecting the magnitude of Space and of the Heavenly bodies, the constitution, form, and motion of the Earth, the functions of the Sun and Moon, the distances of the Sun and fixed Stars, the nature of eclipses and comets; and a great many other matters. In terrestrial physics, the mental advances have been equally great in our ideas respecting the causes of tides and of winds, the pressure of the atmosphere, the existence and course of the Gulf Stream, the physical conditions of the Equator and Poles, the conditions upon which day and night, summer and winter depend, the depth of the ocean, the height of the atmosphere, the cause of rainbows, of {86} rain, hail, snow, mist and dew, of thunder and lightning, the composition of air, water, mineral, and organic substances, and other most numerous and varied phenomena. In the subjects of heat, light, electricity, magnetism, chemistry, vegetable and animal physiology, psychology and morality, and the more concrete subjects depending upon them, such as politics, trade, commerce, government, &c., our ideas have equally advanced, in consequence of scientific research; and to fully describe the mental progress resulting from discovery in nearly all branches of human knowledge would require a series of books to be written on the History of all the Sciences.

Other causes also, which I need hardly mention, besides scientific discovery, have of course contributed to the mental progress of mankind. We arrive at true ideas, not only by the more certain and systematic process employed in scientific research, but largely also by the uncertain method of trusting to instinct and habit, by adopting dogmatic opinions, and by the semi-scientific plan of following empirical rules.

Dogma and empiricism, in nearly all subjects, has rendered immense service to mankind. Contemporaneously with the progress produced by new knowledge, the mental condition of man has been maintained and prevented from receding, by the combined influence of hereditary mental proclivity, acquired habit, promulgation of dogmatic opinions and empirical rules, and by previously known verified truth. Religious {87} belief has thus been the forerunner of Science. Dogma and empiricism are indispensable agents of civilization; they cannot be dispensed with by the great mass of mankind, who have not the time at command, nor possess the other means, necessary for acquiring verified knowledge. They afford rough and ready guides and useful "rule of thumb" methods, though less certain and less accurate than those afforded by verified and definite science.

That various inventions, based upon scientific discoveries, have greatly aided and extended our mental powers is quite certain. The discovery of the properties of a mixture of solution of nutgalls and green vitriol, has, through the invention of ink, exercised an immense influence in promoting the mental developement of mankind; and the discovery of the properties of esparto grass and other materials for making paper has contributed to this result. Every discovery also resulting in inventions which facilitated the transmission of intelligence has had a similar effect. Amongst these are magnetism, which, in the mariner's compass greatly assisted navigation and the conveyance of letters by sea; and the steam engine which facilitated the transmission of letters by land and by water; the electric telegraph, the telephone, and other contrivances for transmitting ideas, have also greatly promoted mental advance. The steam engine, by largely abolishing physical drudgery, gave time for study and mental and moral improvement. It has been said that "it is impossible to lay down a {88} railway without creating an improved intellectual influence. It is probable that Watt and Stephenson will eventually modify the opinions of mankind, almost as profoundly as Luther and Voltaire." Photography has exercised an immense intellectual influence of an improved kind, by making common to all mankind views of the beautiful scenery of all parts of our globe, and portraits of individuals of all nations and of all classes of society. Processes of printing from electrotype plates, pictures and letter-press, upon the paper wrappers used by grocers and other tradesmen, have also carried into the homes of millions of poor persons truthful ideas and an improved intellectual influence. The invention of steel pens, of which a thousand millions are made yearly in Birmingham alone, must also have considerably aided intellectual progress. The various calculating machines used by merchants, the copying presses, papyrographs, and the numerous inventions for copying and multiplying letters and circulars and for domestic printing, have saved intellectual toil, and promoted the diffusion of intelligence. These are only a few of the numerous ways in which inventions based upon scientific discoveries, have resulted in mental progress.

Less perhaps has been done in the way of actual definite scientific experiments upon mental actions and processes than in almost any other department of science, and this is partly accounted for by the fact that the other sciences require to be largely advanced before we can use them to examine mental action, {89} and partly also because (as occasionally happens) the latter has been a neglected subject of research. During the past few years however, various experimental investigations have been made, especially by Donders in Holland, and Mosso in Turin, for the purpose of elucidating the physical conditions of mental action; and it has been found that instead of an act of thought being instantaneous, as was formerly believed, it requires a variable time.[13] Numerous desultory experiments made upon dreamers, and with drugs, alcohol, &c., upon persons in the waking state, also prove that mental phenomena are amenable to scientific research. F. Galton has even proposed experiments and methods for measuring the mental faculties of different persons.[14] The effects of exciting different parts of the brain of animals by means of electric currents, and the localization of the functions of the brain effected by the experiments of Ferrier, Hirtzig and others, also tend to throw further light upon mental phenomena. The fact alone that mental actions and conditions may be made the subject of experiment, and consequently of observation, comparison, analysis and inference, proves that they may be rendered sources of new facts and principles, and are therefore within the domain of science. As the dependence of mental phenomena upon physical conditions has been clearly demonstrated, an extensive reduction of them to scientific laws is only a question of time and labour.

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The principles of nature and the modes of mental action are the same for all men. It necessarily follows from the essential nature of truth and the invariability of the chief methods of detecting it, that the criteria of truth in mental science, and the mental powers and processes by which truth is arrived at and detected in that science, are essentially the same as in the physiological, chemical, and physical ones. In each of these subjects, we first, either with or without the aid of experiment, make observations, record facts, compare them, and draw conclusions from our comparisons; we also group the facts, and the conclusions, in every possible way, and then draw other conclusions; we also analyse, combine, and permutate the various truths arrived at, and cross examine the evidence in every possible manner in order to extract from it the greatest amount of new knowledge. And in each case we employ as the criteria of truth, the test of consistency with the whole of the evidence bearing upon the case, and especially with the great principles of science. We determine what is true, chiefly by comparison with those principles, because they are the most firmly established true ones and the most universal. There is no royal road to truth, and no special mental faculty for detecting it in any subject; and it is in consequence of our mental faculties being so very finite that we have no easier way of arriving at truth.

No dogmatic teaching can ever, except by accident, fully explain to man the true nature of mind; and {91} only in proportion as man becomes enlightened by extension of new scientific knowledge, especially in physiology, will he be able to view himself in a true aspect apart from his consciousness. Science penetrates deeper than metaphysical speculation, into the nature of mental action, chiefly because metaphysics deals only with old ideas, whilst science furnishes us with new experience and therefore with new conceptions and wider evidence.

Fallacies are very prevalent, every subject of human study is liable to a very large class of errors arising from the extremely imperfect state of our knowledge, and in very few subjects is our ignorance as great as in that of mental and moral phenomena. Every different subject of study also, has, in consequence of its special peculiarities, its own peculiar class of fallacies, into which the student of it is likely to be led, unless he is previously guarded against them. In accordance with this truth, the study of man's nature, especially the mental and moral portions, is particularly liable to a class of errors arising from the circumstance, that the phenomena to be observed and the observing power are intimately connected together, each influencing and disturbing the other. The obstacles to our arriving at truth in the study of mental and moral actions, are greater and more frequent, the more nearly and intimately related the phenomena to be observed and contemplated, are to the observing and contemplating faculty, or rather to the contemplative action. When the two mental {92} actions are extremely intimate, as when attention is directed to the action of will (which is itself a conscious act of attention) undisturbed thought becomes very difficult; and when further, the contemplative faculty attempts to contemplate itself, as when consciousness attempts to observe consciousness, in order to define it, the attempt results in almost complete failure, probably because the two actions (observing and being observed) being opposite in kind, cannot coexist at the same time in the same structure. Knowledge of the exact nature of consciousness therefore, will probably only be arrived at by indirect means, when physiological and other knowledge is sufficiently advanced.

Consciousness, when uncorrected by sufficient knowledge and inference, is a great source of error. That which we feel, we think exists whether it does or not, until the subject is correctly explained to us. The incessant and irresistible obtrusion of consciousness exercises dominion over every mind, even of our greatest thinkers, and causes disturbance and interruption in nearly every train of thought. It is largely the cause of some of our most general ideas and emotions and insensibly influences our views of man and nature. It produces true impressions as well as erroneous ones. It is a cause of the feeling that an occult spirit exists within us independent of our material structure. Combined with the almost equally persistent impression of the uniformity of nature, it largely produces the idea that the spirit within us, {93} will live and be active for ever. And by uniting with the frequent impressions of failure of our efforts and desire for more perfect enjoyment, it largely originates the idea of everlasting happiness.

It is in accordance with modern scientific knowledge, to view the mind, not as a collection of distinct faculties, but rather as a single kind of power, like each of the physical forces, having several different modes of action; and as that which perceives, thinks, and wills. Its oneness is shewn by its inability to be simultaneously occupied by several diverse feelings, thoughts, or volitions, and by our incapacity to think of many varied ideas at once; the more ideas also or objects we attempt to perceive at once, the less we realize of each. In proportion as the mind is engaged upon one idea, so is it also unable to be occupied with another. Strong feelings exclude intellectual action. The mind can only execute several actions at a time, provided they have been rendered more or less automatic by habit, &c., but as all mental acts are in different degrees imperfectly automatic, and require more or less attention, and each individual mind is limited in its power, every such act withdraws a portion of attention from the more engrossing ideas. Power of mind and power of maintaining attention are nearly synonymous.

The recognised fundamental elements of mind are Receptivity and Perception of impression: Retentiveness of impression: Perception of agreement (or similarity) of impression: and Perception of difference {94} of impression. All purely mental acts appear to be resolvable into these.

Many persons still entertain the idea that mental actions are largely independent of the natural conditions to which physiological, chemical, and physical phenomena are subject. The unscientific mind is readily beguiled by easy schemes of mental action, or simple systems of mental and moral philosophy, unaware that great abstract truths often require deep thought to discover them, or even to perceive them when discovered and published. "A false notion, which is clear and precise, will always meet a greater number of adherents in the world than a true principle which is obscure." It is not until unscientific persons have become used to advanced scientific ideas and nomenclature, and knowledge as so far progressed as to enable thinking men to illustrate those ideas freely in familiar language, that great abstract truths are believed by the public. The ordinary and simple theory of the operations of the human mind is, that they often arise without any cause, and are frequently not obedient to ordinary influences, and this idea is still entertained and promulgated even by some of our most popular ministers of truth. It is therefore necessary in order to further prove that new scientific knowledge is really a basis of mental progress, to point out a few of the chief ways in which mental action essentially depends on scientific principles, and to adduce a few instances in which other substances than brain exhibit essentially similar phenomena. To {95} shew this however in a more satisfactory manner would require a large treatise to be written upon the subject.

The human brain and mind are evidently subject to the ordinary laws of matter and energy. Receptivity and retentiveness of impression is not only a property of brain, but of all solid matter without exception. Moser's pictures, and Chinese mirrors, the impressions on each being reproducible by warm breath, are examples of this. And as these two properties are fundamental elements of mind, they must be present in and essential to, every mental action.

All phenomena require time and all matter occupies space; thought and brain are no exception to this. Whilst all persons say "I must have time to think," many believe that thought is instantaneous. Time is a necessary condition of all thought, and therefore of all comparison, inference, imagination, and mental analysis; it takes time even to form an idea, or draw an inference from it, and the two cannot be formed simultaneously. Professor Donders, of Utrecht, has invented what he terms a Noematachograph for registering the amount of time occupied in mental processes, and by the aid of that instrument has ascertained that the time required by a man of middle age to perform a single act of simple thought is about one twenty-fifth part of a second. It has also been ascertained that the time required is longer in some persons than in others; and longer if the {96} subject of thought is one with which the thinker is not familiar. Mosso, by means of an instrument which he calls a Plethysmograph, has shewn, that during mental action, either in the waking state, or in dreaming, there is a greater amount of blood determined to the brain, and more during difficult than during easy mental action. These are instances of scientific research casting a light upon mental processes.

Coexistence of matter and energy is another great truth which appears to be applicable to all nature; wherever there is matter, there is either active or stored up power; and as particular forms of energy are in some cases most exhibited by particular kinds of substance, (as magnetism by iron), so mind is associated with living brain. As also we never see the physical powers exhibited except by material substance, so have we never yet observed mental action in a space devoid of material. The most perfect vacuum yet produced contains many millions of particles of substance in each cubic inch. Of all the countless number of scientific phenomena observed since men have been able to reliably investigate, not one has afforded us conclusive evidence of mental action entirely independent of these conditions. In accordance also with the usual truth in science, that complicated action requires complex structures; mind, being the most intricate action, is manifested by the most complicated body.

Mind, like each of the physical forces may be {97} viewed as a mode of energy; it is essentially dynamic; activity or change, within or without us, appears to be the original source of all our mental impressions, and the cause of their re-excitement in an act of memory. A man's mind, being continually excited by circumstances, must be active whether he will or no, and if it does not possess sufficient truthful ideas entirely to occupy it, it must be more or less occupied with erroneous ones. "We can neither feel, nor know, without a transition or change of state--and every cognition, must be viewed as in relation to some other feeling, or cognition," (Bain. Mental and Moral Science, p. 83); _i.e._ the mental effect of impressions upon us depends upon our immediately previous mental state; consciousness and perception appear to be based upon cerebral change or activity; after strong excitement of consciousness an increased amount of acid products is found in the secretions. "It is a general law of the mental constitution, more or less recognised by inquirers into the human mind, that change of impression is essential to consciousness in every form," (Bain. Emotions and Will, 3rd edi. p. 550). A sufficient degree also of such change is a necessary condition of conscious perception; it is the stronger or more rapid only of mental changes that excite our consciousness.

We perceive nearly all things by means of a difference of impression which they make upon us; by contrast. That which makes no such difference of impression, such as the great uniformities of time and {98} space, makes no immediate impression upon us. We only know of the existence of those uniformities by inference from our perceptions of sequences or of relative difference. Although the Earth moves at the rate of 62,000 miles an hour in its orbit, consciousness does not perceive it. If also there was no error, we should be less immediately able to discern truth, without pain we should lose much of the enjoyment of pleasure. Without the contrast of imperfection we could not directly appreciate perfection.

This principle of "relativity," or of change of impression, operates both in the phenomena of dead and living matter and in those of mind; the selenium in a photophone is kept in a state of motion or activity, not by a beam of uniform light, but only by one which changes; electrical action is excited by a relative difference of friction, of temperature, of chemical action, &c.; chemical action also often results from a relative difference of property of two bodies. That the most inscrutable phenomenon of mind, viz., consciousness, is largely dependent upon relative physical and chemical conditions, is proved by the powerful influence which alcohol, chloroform, opium, haschish, and other substances, have in exciting or depressing it. These facts prove that excitement of consciousness or mental action depends upon precisely the same general condition, viz.: change of impression, as the excitement of some of the physical forces; and that mind possesses a similar property to the physical forces of being changed by inequality of impression. {99} Whilst copious evidence is available to shew that the mind is excitable by physical causes, no more conclusive proof exists that a mental impression arises without a natural cause, than that a physical one, such as a photographic impression, arises in that way. Abundant evidence of non-creation of ideas out of nothing might be adduced; even imagination and invention are subject to this limit, because an unlimited number of new conceptions cannot be formed from a limited number of previous ideas.

The dependence of the mind (like any other mode of energy) upon physical conditions, is further proved by the fact that the mental and moral states of a man are largely governed by sensation; if the latter is unhealthy it makes the mind so, and it makes some difference what the part of the body is in which the sensation exists; most commonly it is the viscera. The mind is also intimately dependent upon the physical condition of the brain, and is largely affected by the quantity and quality of the blood in that organ.

The most fundamental principle which pervades every one of the sciences, and agrees with the actions of every natural form of energy without exception, including mind, is, that of consistency or non-contradiction. No machine or scientific apparatus of any kind can perform two contradictory acts at the same time. It is both a physiological and psychological fact, that we cannot experience two contradictory sensations, nor perceive two contradictory ideas at the {100} same instant. We can neither feel, perceive, nor observe, one thing, whilst we are feeling, perceiving, or observing, one of a contradictory nature; nor can we perform any two contradictory acts of comparison, inference, imagination, or volition, simultaneously. As also two mental actions are often not exactly alike, or entirely harmonious, they must so far as they are really contradictory, be mutually exclusive; and one of them must partly prevent the other, the strongest one prevailing, and this general truth is commonly though not explicitly, recognised in the maxim, that to do anything well, we must do only one thing at a time. In accordance with the universal truth, that contradictions cannot co-exist, it is well-known that one disease frequently expels another from our frame, and the action of counter-irritants is based upon the same principle. The fortitude of martyrs may probably be explained by this power of one set of ideas and feelings to exclude another, and the facts of mental physiology afford plenty of other examples.

It is probably because we cannot simultaneously perform two contradictory actions, that we cannot contemplate consciousness, or think of an idea and at the same time think of that act of thought. In accordance with this, even Newton, and other great geniuses, have been unable to accurately describe the mental processes by means of which they arrived at their most difficult results. In consequence also of this, we cannot define consciousness, and are often {101} unable to directly observe or analyse our mental actions, especially those of a very abstruse or complex kind. Much of the knowledge of the operations of our mind, we are therefore obliged to obtain by indirect means; by analogies, and inferences from the phenomena of nature, &c., and in this way our knowledge of mental action largely depends upon our acquaintance with physical and chemical science, and can only advance as it advances. To clearly understand one subject we are often obliged to study several others. Ignorance of science in general, and of cerebral physiology in particular, is the chief obstacle to our acquiring a more accurate knowledge of mind.

Next to consistency, the great principle of causation constitutes the most essential part of all natural truth, and to deny the operation of this principle in particular cases of mental action, simply because we, with our very finite powers, cannot in the extremely imperfect state of our knowledge, yet fully explain some of the most difficult, complex, transient, and ever-changing phenomena of will and consciousness, is contrary to the most weighty evidence. "The Will" is a conscious mental effort to effect an object, the idea of which is already in the mind, and being a mental "effort" it absorbs the mind and thereby incapacitates it at the moment from observing its own action.

If any phenomenon (such as mental action) is essentially dependent upon another, it must be connected {102} with it in a never-failing or indissoluble manner, so that when the one occurs the other is always present, otherwise it would not be essentially dependent. The only known connections of this kind are those causation and continuity of phenomena, according to which every phenomenon has a cause, and all phenomena are indissolubly connected in endless series. The evidence of the truth of these principles is so vast, that even all mankind thinking through all ages, and after having made an almost infinite number of definite experiments and observations, have never yet met with a single well verified instance of their failure; and we are therefore justified in inferring that they are universal. There are however instances in the physical and chemical sciences, as well as in mental action, where the dependence of phenomena upon those principles is not very apparent, and has not yet been sufficiently proved, but it is probably in consequence of our imperfect knowledge and limited faculties, that we are unable as yet to fully trace such dependence. The history of science, abundantly proves that we should not assume that a phenomenon arises without a natural cause, simply for the reason that it is very difficult to trace its origin, but wait patiently for more knowledge respecting it. It is unphilosophic and contrary to reason to attribute to occult agencies, effects which may be explicable by ordinary causes, or to refuse to believe in more abstruse causes where the assumption of simple ones is contradicted by some of the evidence. {103}

The principle of causation forms the basis of many minor ones, such as selection, evolution, differentiation, &c. Plurality of causes also is a very common circumstance in all the sciences, and especially in concrete phenomena, and in the complex ones of animal life; the arrival of a ship for example at a distant port, is a result of many conditions. Similarly with most of our mental actions, they are compounds of feeling and intellect, and produced by many causes, such as hereditary tendency, acquired habit, internal and external mental excitants, dogmatic belief, knowledge of empirical rules, and occasionally of verified principles. Several of these causes also frequently conspire to produce a single idea or decision.

Various general principles of lesser magnitude arise from the combined action of two or more of the greater ones, and these also appear to operate in mental actions as well as in physical ones. Thus by the combined influence of causation and of the principle that every phenomenon occupies time, "effects often lag behind their causes;" and in some cases during a long period. The greatest heat of summer for example usually occurs several weeks after mid-summer. The mental effects of early mistakes are often not fully experienced until old age. The decline of a nation also follows a long time behind the period of action of the chief causes which produce it.

Although effects are indissolubly connected with their causes, they frequently do not occur in an active form until a long period after them. In such cases {104} they are stored up in what is termed a potential or latent state, ready for liberation at a future occasion, when the suitable conditions are present; the storage of chemical power in gunpowder, of solar heat in coal, and its subsequent liberation in our fires, are suitable examples. The principle of deferred activity and storing up of power, occurs also in vital and mental phenomena; potential heat is stored up in our food, and is afterwards evolved by oxidation in our tissues. Muscular power is stored up during sleep, ready to be evolved during labour. The storage also of cerebral impressions, and cerebral energy, ready to call forth ideas, and thereby powerful emotions, by the exciting action of memory, may also be viewed as an instance of similar kind belonging to mental phenomena. A new and striking instance of the storage of energy has been shewn in Faure's improved form of secondary voltaic battery, in which the most powerful voltaic current may be (at least practically) stored up (in a box containing lead plates immersed in dilute sulphuric acid) and conveyed to a distance with little loss, and then liberated.

Exciting causes operate very extensively in mental actions as well as in physical ones, a mere look or word from an eloquent speaker will excite the passions and liberate the muscular power of a multitude. Every part of the human body, especially the muscles and nerve centres, is a store-house of power always ready to be set free by the slightest suitable causes; this is strongly illustrated in the irrepressible activity {105} of children, and in the excitable passions of young men and women. The more immediate cause of this power is the oxidation of assimilated food; and the source of power in the food is the heat of the Sun stored up in the plants and animals they have eaten.

The subsequent liberation of power under the influence, often of very slight causes, long after the original cause has ceased to act, has led us to conclude erroneously that causes are not always proportional to effects. Proportionality of effect to cause appears to be universal; it probably operates in mental as well as in physical actions, our faith in education as a means of intelligence is based upon this; the more complete the education of a particular individual, the greater usually is his degree of intelligence. Proportionality of cause to effect is apparently disobeyed not only in physical but also in mental phenomena. Throughout the whole realm of nature, minute circumstances often act as exciting, deflecting, and guiding causes, and contribute to the production of apparently disproportionate effects. Thus a spark will discharge the largest cannon; a touch determine the most distant electric signal; a word or look, excite the strongest emotions; the little change of position of a railway point will direct a train either to distant North or South; the minute change of contact of the telegraph switch, will determine the signal to places wide asunder; one false idea also at a critical moment will often lead a man or woman to ruin; and in all these classes of cases, {106} whilst trifling causes _appear_ to produce great effects; the real causes are the stored up latent powers set free or directed. It is astonishing how small a circumstance will excite an idea, and deflect the entire current of our thoughts; and it is equally surprising what great physical and chemical effects are often started by most minute exciting or deflecting conditions; the explosion of seven tons of dynamite at Hell-gate, near New York, by the pressure of a child's finger closing an electric circuit is a suitable example.

Every phenomenon therefore whether physical or mental, is probably connected in an indissoluble manner with some preceding phenomenon, either immediately in point of time, or remotely through some static condition, usually that of stored up power. In this sense the great principle of continuity of phenomena appears to be universal, and the present state of the Universe is said to implicitly or potentially contain all the future states of the Universe. Mind also in this way, like each of the physical forces, often acts as a link in an endless chain of causes and effects, and is connected with non-mental phenomena in accordance with the great principles of science.

Science has demonstrated what has been termed the "Convertibility of Forces," or, that when one form of energy disappears, another form (or forms) of energy, and in precisely equivalent amount, is produced in its stead, either in a latent or active state. The equivalent quantities of the various forms of {107} energy have also been discovered by actual experiment and measurement. A pound weight falling through 772 feet gives forth as much energy as would (in the form of heat) raise the temperature of one pound of water one Fahrenheit degree. We know that so much mechanical power is equal also to so much electric current, chemical action, &c., and a large amount of evidence exists to show that these transformations of energy occur in all the organs of living creatures, and in obedience to the law of their equivalents. How far mental power is a "mode of energy" transformable, and obedient to the laws of equivalence, are interesting questions for future research.

The mechanical principle of action and reaction is another which can be traced in mental as well as in physical phenomena. Mental excitement is often succeeded by mental depression, "after pleasure follows pain." The power of mental self-guidance and self-education is largely dependent upon the two well known scientific principles of latent energy, and action and reaction. We are able to liberate energy, not only in cases where it will influence inanimate matter but also ourselves. The principle of self-guidance is not restricted to living creatures, nor is self-regulation limited to mental power. The principle of self-regulation operates in clocks, watches, musical boxes, the governors of steam engines, water regulators, gas regulators, &c., &c., and upon an immense scale in the movements of the heavenly {108} bodies. With the electric locomotive, the greater the load it has to draw, or the steeper the incline it has to ascend, the more strongly does it exert its strength, up to the full limits of its power. Neither in physical nor in mental actions can a body or force usually act directly upon itself to change its state whether of activity or rest. In both classes of cases however we meet with plenty of instances where, a body by an almost imperceptible expenditure of energy on its own part either alters some surrounding conditions, or excites a powerful liberation of energy in another body which then reacts upon it to change its state. In this way the action of clock-work in the self-exploding apparatus of a torpedo liberates at a particular moment a spring, and causes an explosion which destroys the apparatus. Similarly, whilst a man, in many cases, is unable to _directly_ alter his mental state, to increase or diminish his mental activity, to cause sleep, &c., he is able _indirectly_ to change his mental condition by drinking stimulants or by adopting means of self-education; and to induce sleep by means of opium, suitable exercise, &c.

The principles of indestructibility or conservation of matter and energy, flow from the preceding ones, and are exhibited in mental actions as well as in physical ones. Whilst the universal experience of mankind has not yet afforded us a single well verified instance of actual creation or destruction of matter or energy, it has supplied us with plenty of examples of apparent destruction and creation of each of them. {109} But scientific knowledge corrects the uncertain testimony of consciousness; whilst we see coal burn and be apparently destroyed, science proves to us that the elements composing it remain undiminished. We observe also that the heat of the fire dissipates and is apparently lost for ever; but science again proves that it is either stored up in the latent state, ready to be again liberated at a future time, or else converted into other forms of energy. A given atom of matter or a portion of energy, therefore, to the best of our knowledge, continues and persists for ever. As we cannot either create or destroy matter so also can we not create or annihilate energy, and this truth probably holds good with regard to mental as well as to physical and chemical power. Great changes of state in bodies (as in the combustion of wood &c.) have led us to erroneously think that the substances are destroyed; and great apparent differences of property, such as those of diamond and charcoal, have led us similarly to conclude that they are entirely distinct and independent of each other when they are not.

As the cerebrum of man is composed of matter, and during excitement, its parts are active, we might confidently predict that its particles obey the First law of Motion, viz.: that a body in a state of rest or motion will continue in that state of rest or motion until some cause arise to prevent it. So it has been found that the action of the vital and mental forces have a degree of persistence, like the physical ones. It has been experimentally found that portions of {110} living bone transplanted to fleshy parts of animals where there was no bone, continued to grow for a time by a life of their own, and increased by formation of additional bone, like a crystal grows in its medium; but after a time they diminished and disappeared. In a similar manner we are all of us aware of the persistency of ideas, even in opposition to the will, after the cause of them has been removed. Sometimes we cannot retain an idea because of the persistence of others; and at other times we cannot get rid of one, for a similar reason. Our mental habits also have often very great persistence.

The principle of heredity may be viewed as a result of the First law of Motion, and appears as Persistency of state, either of structure, form, or mode of action. It appears both in inanimate bodies, living structures, and in mental phenomena; in the latter, as hereditary mental peculiarities. The principle of Persistency of structure and Heredity of form and property, during repeated or even continual dissolution and aggregation of a material substance, is more or less manifest nearly throughout the whole of nature. In the formation of crystals it is clearly seen; each crystallizable substance will only grow into its own shape or shapes; each particle of common salt, during an endless series of successive solutions and aggregations into the solid state, always forms a more or less perfect cube; that of silica a hexagon; and so on throughout the entire series of thousands of different crystalline bodies. As each {111} form of crystal only produces crystals of like form and property (or at most in certain cases a limited number of modified forms, as in the instance of calcic carbonate, &c.) so also each seed, both of animals and vegetables, only produces its own particular essential shape and collection of functions. The same principle shews itself in the transmission of particular types of disease, and of eccentricities of organization, from one generation to another of animals. Peculiar malformations of body and characteristics of mind often persist in families from generation to generation. This persistency or heredity of structure and of property is not limited to solid bodies, but exists also in liquids: "The effect of vaccine virus upon the liquid blood, in producing a permanent and organic change in its constitution and character, which continues to exercise a protective influence against small-pox, in the great mass of cases, through a long life, during which time the blood must have undergone, many thousands, if not millions of changes and modifications." (F. Winslow. "Obscure diseases of Brain and Mind," page 432). The same persistency of structure and property of structure, has even been detected in vapours; the vapour of red iodide of mercury for example, deposits only crystals of red iodide, whilst that of the yellow deposits only yellow (see Gmelin's Handbook of Chemistry, vol. 1, p. 100.)

We often appear to mentally select when we only yield to causes acting upon us, _i.e._, to the strongest influence or motive. That "self-preservation is the {112} first law of nature," is not only true of living creatures, but largely also of dead substances. Inanimate as well as animate matter, appears to usually select what is good for itself. Apparent selection, which is manifested in the phenomena of instinct, is exhibited not only by brain, but by all material substances. Acids appear to select bases, North magnetism rejects North and prefers South magnetism. Also if a piece of zinc is put into a mixed solution of the nitrates of silver, magnesium, calcium, strontium, barium, lithium, sodium, potassium, and rubidium, it will select the silver only with which to form a "metallic tree," and reject all the other metals. Everything which aggregates or grows to a definite shape, appears to select its material; if a crystal of a particular salt is placed in a mixture of saturated solutions of different salts, it will only select and assimilate to itself suitable material, either particles of the same composition as itself, or those which are isomorphous with it, _i.e._ belonging to the same crystalline system. In living bodies also, the same principle operates; Living tissues, whether of animals or vegetables, usually select from their nutrient fluids, and assimilate, particles only of those kinds of matter which are suitable for their structure; in this way, a bone assimilates lime and phosphoric acid from the multitude of different substances conveyed to it by the blood. And in all these cases, the selecting material appears to act as if it possessed the powers of instinct, perception, comparison, judgment, and {113} volition. The act of self-repair is clearly connected with this, and is not limited to living structures; Sir David Brewster observed that if a portion of the surface of a perfect crystal of alum is very slightly abraded by dissolving a film from it, and the crystal be then immersed during a very brief period in a saturated solution of alum, the abraded portion repairs itself. The subjects of "malformation of crystals," and "diseases of crystals" have been scientifically investigated. The power of selection (or rather of apparent selection) is no doubt a result of the combined action of causation and of the inherent properties of bodies, and depends, like consciousness, upon difference of impression, the strongest suitable influence determining. If apparent selection can thus be performed by inanimate matter, we should not, except for a very sufficient reason, assume the existence in living creatures, of a special occult power to perform the same function. In the selection of ideas also the intellect acts according to the purely scientific method.

We frequently appear to mentally adapt ourselves to particular circumstances when we are really determined by causes; and this apparent adaptation is also seen in ordinary physical and chemical phenomena. The course of a river for instance, adapts itself to the configuration of the country through which it flows, and if it cannot pass wholly by one channel, as in seasons of flood, or on occasions of accidental obstruction, it travels through several; and a similar result {114} occurs with the flow of the blood when an artery is tied or becomes obstructed. A plant when growing in a dark recess, bends itself towards the light as if it preferred light; and its roots adapt themselves to the forms of existing obstacles. A decapitated frog jumps away from a source of irritation, as if he still possessed sensation, volition, and choice. A man seeking his way through a crowd avoids the course in which the throng is densest. The human mind also, chooses as it were, the easiest way of solving a problem, and usually adapts itself to altered circumstances.

The principle of evolution also operates both in physical and mental actions, and is a result of that of causation. Complexity of structure and function is evolved out of simplicity of composition and property by plurality of causes and conditions. For instance, many complex forms of crystals of ice are produced from water. Calcspar crystallizes in more than one hundred varieties of form, (all derived from an obtuse rhombohedron) under the influence of a number of slightly different conditions of temperature, impurities in the solution, &c. The most complex bodies are evolved out of the simplest, the bodily frame of man himself (and that of other animals) is constructed of less than twenty of the elementary substances. The same simple substances are capable of yielding very different and more complex bodies under different conditions; thousands of different chemical compounds are composed of hydrogen, oxygen, and carbon only. In the development of {115} living forms from ova, the ultimate form produced does not exist in the germ, any more than a crystal exists in its solution, but is a natural consequence of the forces acting in and upon the germ, like the cubical form of a crystal of common salt is a result of the forces acting in its constituents under the conditions of its environment, especially those of pressure and temperature. The extent to, and manner in which, the force and principle operate, depend upon the material substance, and its conditions internal and external.

It is a common circumstance, both in physical, mental, and moral subjects, for the apparent to be the very opposite of the real. This general truth has been repeatedly illustrated in an incidental manner in this book, and need not be much further elucidated. Phenomena are none the less real, however, because they are not readily manifest; our earth is as much tied to the sun by the invisible power of gravity, as if it was attached to it by visible material chains. Mistaking the apparent for the real, largely explains the persistency of certain beliefs, and why it is that persons unacquainted with science, cling to self-deception, and resist some of the most firmly established truths. The more evident but untrue explanation is believed, whilst the less apparent but true one is rejected. It is the chief cause of the belief that "the will is a supernatural power." To a scientific man however, apparent contradictions are not unfrequently a sign of truth; too accurate results sometimes {116} indicate that they have been artificially made to appear correct.

Sympathetic action or propagation of similar influence by immediate impulse, is a property of all the natural forms of energy, as well as of mind. Similar actions are propagated thus in all kinds of dead substances, as well as in the living brain. Matter is sympathetic to sound in the phenomena of singing-flames, and a vibrating string responds to a particular note in obedience to well-known laws. Iodide of nitrogen may be caused to explode by the influence of a particular note from a fiddle. In the phenomena of light, with a spectroscope, a luminous gas is sympathetic with, and emits and absorbs, only particular kinds of luminous rays. In chemical action also, combustion excites combustion, ferment excites ferment, infection communicates infection, and the similar chemical change is transmitted from molecule to molecule. Mental excitement and disease in one person, often excite similar phenomena in another, as is seen in "religious revivals," and well-known epidemics, such as the "dancing mania," "preaching epidemics," the "leaping ague," the "mewing contagion," etc., etc., (See "Epidemics of the Middle Ages," by Hecker; Sydenham Society publications; also Carpenter's Mental Physiology, p. 312.) Like excites like in the actions of each of the forces of nature; both in physical, chemical, and mental action, the kind of impulse transmitted is similar, unless conditions exist which transmute it. Dynamite, {117} started into combustion by a flame, burns slowly away; but when started by a detonating substance, detonates violently. Guthrie has also discovered that if a melted cryohydrate (_e. g._ a chilled saturated aqueous solution of a solid salt) is cooled to a certain greater extent, it will not solidify--nothing separates out, although the solution is four or five degrees below its proper solidifying point. If a little crystal of ice be then thrown into it, nothing separates but ice, which comes to the surface. If we throw in a little anhydrous salt, nothing but the anhydrous salt separates out, and that sinks to the bottom. But if we throw into it a crystal of a previous crop of cryohydrate, then nothing but the cryohydrate separates. In this case also, like evidently excites like only, in obedience to physical laws. (Addresses, Science Conferences; South Kensington Museum, 1876; Vol. 2, p. 108). Even two clocks, when hung near each other, against a board or surface which readily transmits vibrations, have been known to exhibit, by synchronous action, an apparent sympathy, which changed their rate of going.

Periodical phenomena, also, brought about by definite causes, occur in mental, as well as in physical phenomena. In the former we have the phenomena of sleep, and in the latter, definite causes produce summer and winter, day and night, the tides, cycles of solar spots, maxima and minima of magnetic intensity, etc., etc.

Conversely to the manifestation of the principles of {118} inanimate matter by living bodies and in mental action, so have modern inventions demonstrated the possibility of the performance by inanimate substances and apparatuses, of the functions, not only of our bodily organs, (as of locomotion by the steam engine,) but also of our senses and intellect, and in some cases, to a degree far surpassing unaided human power. Apparatus, sensitive to sound, have been constructed, as in the microphone and singing-flames; others capable of reproducing articulate speech, as in the phonograph, telephone, etc.; others again sensitive to light, as in the production of visible images by photography, and reproducing them at a distance through wires by means of the photophone; the power of indicating or foretelling future events has also been embodied in instruments called "tide predictors," and that of evolving inferences has been shewn in Jevon's "Logical machine."

The various facts mentioned in this chapter prove that mind agrees with the various forms of physical energy in many essential points, and obeys many of the same laws or principles. Examine whatever general phenomena of the mind we may, we can always detect some apparent or real connection of them with the great principles of inorganic nature; and in order to prove the dependence of them upon the great principles of science it is not necessary to show that all such actions are subject to those principles. Until the whole is explained however, there will always remain mysterious phenomena to cavil about. {119}

MORAL PROGRESS.

At the present time few competent persons have largely investigated the fundamental relations of morality to Physical Science, consequently moral actions are usually considered not to have a scientific basis, and the doctrine is still extensively taught that some moral phenomena are essentially supernatural.