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of the navigator, who has valuable lives and property at their mercy. This great practical stake has been a very strong motive to acquire correct knowledge of the heavenly bodies; and the habits of accuracy that have been once engendered by practical wants come to be extended to portions of the subject having no immediate bearing on practice.
The actions of men are partly instinctive, partly imitative, and partly ruled by their own personal experience, and by the experience of others, communicated by speech or writing. Eating, walking, pursuit, fighting, and loving, are instinctive emanations of the human soul. Education and imitation communicate numerous well-known faculties. Personal experience goes for a great deal in every one's life ; indeed instruction imparted from without has but little efficacy till actual experience has clenched the lessons. The acquisition of other men's experience supposes that the facts of the outer and inner world have been expressed in intelligible speech-a most important step in human history, marking the period when the knowledge of successive generations could be accumulated and preserved, and when the human race should become like one immortal, growing in age and wisdom, but ever fresh and green.
The idea of expressing all knowledge, experience, and wisdom in language or speech is so familiar to us that we seldom reflect on the quantity of knowledge that is never communicated, or on the work performed by mere unthinking experience. A man may go through his operations of tilling the ground, thrashing, grinding, spinning, fishing, quarrying, in perfect silence, and without being able to convey in words the experience he goes upon, or the different steps of his processes; these steps being engraved in the habits of his body, without having been ever expressed by his tongue. The eye sees, the hand feels, the body in general acts; the workman knows what he is about, what he wishes, and what he can do; he has spent a life of actual trial and error, and he has learned to take the course that avoids the error, but still he need not speak about it. Description by language is something over and above the skill and wisdom of the workman, be he what he may; and such description is very apt to fall below this wisdom, and to fail entirely in putting others in possession of it. Hence the most skilful mechanics, navigators, soldiers, physicians, rulers, have been unable to leave behind them the record of their wisdom, or to throw their mantle upon their successors by communicating the secrets of their procedure. Not to speak of the impossibility of every man doing whatever he sees another doing, it has really been found impracticable to record all the sensations of a keen eye and a delicate hand, so as to put others in the position to profit by the knowledge of nature thus acquired. A physician may discern symptoms that he cannot by any very verbal description teach his pupil to discern, and thus his skill in adapting remedies may perish with him.
Now it is scarcely necessary to remind the reader that there is neither philosophy, science, nor doctrine possible without speech. No facts or observations can be of any avail in science unless they can be expressed in language. Science must be something that all men can possess; herein it is distinguished from the instincts of the animal creation or the incommunicable knack of the skilled artisan. If there be facts that elude expression, or that language has not yet been adapted to, such facts have
not been brought within the pale of philosophy, however well they may be recognised in practice. The sailor may have a discernment of the signs of the sky over and above any knowledge that has yet found its way into meteorology: to this extent he is ahead of science; but in as far as he is so, his knowledge dies with him, and to his successor it is as if he had never lived.
These observations are necessary to pave the way for the remark, that the existing science of the world at any one time may be utterly useless for any practical end whatsoever, and its pretensions to interfere in practice may have to be denied and resisted. There is usually required a very high degree of advancement in any branch of speculative knowledge to enable it to overbear and correct the experience of the practical man, and if it brings forward premature claims to the direction of workmanship and affairs, the result may be ruinous to all concerned. The Egyptians had acquired by their experience a certain knowledge of land-measuring before the existence of geometry and trigonometry: the theorems of Euclid would have served to increase their powers in this respect to an immense extent; but if in the early stages of geometrical speculation, when only a small number of Euclid's theorems were known, and when perhaps there were fallacious propositions afloat among the cultivators of the science, it would have been purely mischievous for any geometer to propose innovations in the rule-of-thumb practice of the Egyptian surveyors.
The philosopher Aristotle is said to have been jealous of the success of his contemporary Isocrates, the greatest teacher of oratory and special pleading of his time, and to have expressed very great contempt for the narrow doctrines of rhetorical art made use of by this famous rhetorician. The philosopher's own treatise on rhetoric took a far higher flight than any system of instruction hitherto known to professors of oratory, and made å searching analysis into the foundations of the rhetorical art; but it may be doubted whether any direct use has ever been made of this treatise in the art of teaching, or in the actual equipment of an orator or poet. At that stage of the subject, the discussion, although having a practical end in view from the very first, could only be considered as an exercise of intellect, a gratification of speculative curiosity, and a commencement of what might in some future day be productive of great practical results; which results would not come out unless the science were cultivated and studied for a long time without any practical gain. The same remark holds in logic, ethics, and political theories. While in their early infancy, any light that can be obtained from such branches of doctrine is less to be trusted to than the sagacity and experience of practical men having no theory except some narrow generalisations of their own, which, as they never repose on any analysis of ultimate laws, cannot deserve the name of science or philosophy
The practical sciences, or, as we may term them, the branches or divisions of practical philosophy, are such as the following:—the various departments of knowledge made use of in the healing art-pharmacy, medicine, surgery, midwifery, &c.; agriculture, practical mechanics, metallurgy, engineering, architecture, navigation, dyeing, painting, perspective, decoration; the theory of art, education, ethics, logic, rhetoric, politics, jurisprudence, science of history, &c. Each one of these branches of knowledge professes to deliver
the laws and sequences of nature that bear upon a certain object or practical use, and to shew how any desired effect can be produced by the employment of adequate means. Principles adapted to practice are termed rules; the language employed being not so much ‘Nature does so and so,' but do thou this, and that will follow. If an individual is affected with particular symptoms of disease the medical expounder prescribes the remedy, and no more, unless he consider it necessary to give evidence of the efficacy of such a remedy. The departments of ethics, politics, and jurisprudence are all founded on human nature, but none of their professors is called upon to give a systematic account of the whole of human nature: the more they know of man the better; but if they know only as much as serves their own turn, no man can blame them for deficiency.
The theoretical sciences are determined and arranged according to the different kinds of phenomena and events presented by nature. The properties of triangles, circles, and spheres, make a distinct species of information; the relations of numbers in arithmetic and algebra are also a class of things by themselves, although they come into very close relation with the other. The actions of moving bodies are not to be confounded with either of these. Gravitation is a distinct power in nature. It has been from no desire to multiply differences, or to find a greater variety of modes of action in the world than there really is, that a separate branch of knowledge has been constituted under the title of chemistry. So the laws of vitality involve a new phase of nature ; and mind is a still higher development, and a more complex manifestation of creative energy. Theoretical philosophy recognises all these distinctions and varieties of working, and finds a separate place for each ; and its divisions therefore correspond, not to the feelings, wants, conveniences, or ends of man, but to the realities of the world. Whoever would know creation as it really stands, and in the most orderly and compendious form that it is possible to conceive it, must eschew practical men and practical books, and betake himself to the theoretic cycle of philosophy: he will have to study in succession mathematics, physics, chemistry, physiology, mind, and society.
It is equally evident, on the other hand, that the practical sciences are called into being by human wants, and are ordered and adapted accordingly. The existence of a science of surgery does not prove that there is in nature a peculiar and distinct class of actions called surgical; for in fact the forces at work in the processes of surgery belong to the theoretical department of physiology. The practical science of agriculture can include no natural causes but what are professed to be expounded in physical
, chemical, or vital science. Politics, law, and jurisprudence relate themselves to the abstract sciences of mind and society. However much we may multiply branches of applied knowledge, we cannot multiply the powers of nature, nor those leading departments of theoretical philosophy which systematically embrace and expound them.
The accumulated experience of any one craft, profession, or branch of business, distinctly recorded in books for universal information, forms the literature and collective wisdom of that particular department; but it is not every such literary collection of practical maxims and detailed facts that deserves to be called philosophy or science. The Chinese, the Arabs, and other nations had very extensive medical literatures long before anything like a philosophical system of medicine existed in the world. A practical science cannot be formed except by the same methods and precautions as are requisite in a theoretical science. The principles of dyeing, bleaching, or of any other chemical manufacture, must be established by the identical processes of observation, experiment, and inductive comparison, and by the same precautions respecting the use of language, as have to be employed in the investigation of the general doctrines of chemistry. No less care and no fewer repetitions and verifications are called for to determine the cure of a disease than would serve to prove the grandest: discovery in physiology or anatomy. All observations and experiments, and all general assertions, in any practical question, that are not conducted according to the highest rigour of scientific method, as exemplified by the best theoretical inquirers in their respective walks, are in general lost labour. Men may write on medicine, agriculture, ethics, or politics, without end, and establish nothing; just as an infinity of treatises have been produced on astronomy, physics, and mind, whose annihilation might make the world wiser, but could not deprive us of any valuable piece of knowledge.
The only thing that renders the investigation of practical science peculiar and distinct, is the fact that it may, at a certain stage of scientific advancement, be made to repose on theoretical philosophy; in other words, the accurately-ascertained laws of the theoretical departments may serve to predict the sequences in the practical departments. The chemical manufacturer may not require to take upon himself the whole labour of investigating the course of nature's operations in his craft, from the circumstance that theoretical chemistry and the general principles of chemical action have been so far advanced as to determine everything that he desires to know. So a practical science of education might be constructed with little trouble, and with the highest precision, if there existed a previous general science of human nature in a high state of perfection; but where the theoretical foundations of any branch of practice have not been securely laid, there is no alternative for the practical man but to execute a series of researches with all the rigour and precision of the most accomplished theoretical philosopher. If this is not done, there may be a body of maxims and doctrines relative to an art, and these may have a certain amount of probability, or be true in a good many instances, but there is no science, no body of principles, true in all instances and in all circumstances.
The difference between the scientific and unscientific experience and rules belonging to a profession is this: when all the conditions that enter into any one effect have been precisely ascertained, so that it is possible at all times and circumstances to produce that effect, the knowledge of the case is complete; no science can be truer than this. But when the conditions of an effect are not perfectly ascertained, when it cannot be stated what things to employ and what things to exclude, and in what quantities, in order to produce an end, the knowledge is imperfect, and in practice there will be a number of failures. For example, in calico-printing there are certain colours whose production is exactly understood, and can be reduced to general laws of chemistry; such is the formation of a prussian blue. But there are other colours where complex organic substances are
employed, and where the laws and conditions of the effects are not correctly ascertained for the workman's guidance, and hence there is a degree of chance and uncertainty in the result, which is very tantalising. Either the printer, for his own ends, or the chemist, for the ends of science in general and all that hangs on it, will require to institute experimental investigations to get out the precise link of cause and effect out of the complex stream of agencies that are at work, provided neither of the parties can meet the difficulty by the skilful application of some of the laws or threads of causation already ascertained among chemical phenomena.
PHILOSOPHIES OF LIFE.
The notions included under theoretical and practical science do not exhaust all the meanings attached to the name philosophy. There still remain a group of significations connected more immediately with human conduct than any that have been touched on in the two divisions above illustrated. As we have not extended the scope of practical science so far as to take in the direct and immediate guidance and pilotage of man's own life, we require still to make some observations on this department, with the view of shewing when and how the idea of philosophy is connected with it.
The immediate impulses, or prime movers of human action, are the natural instincts, passions, emotions, and energies of the human constitution. The likings and aversions, and all the potent stimulants that act on our frame, are the influences most easy and congenial to yield ourselves up to. The fact, however, is, that if we abandon ourselves at random to each prevailing impulse that seizes us—hunger, sleep, violent exercise, anger, sympathy we shall soon terminate our existence in a wreck. Among the moving powers that act on us we must suppress some and regulate others; we permit one to have a larger sway than the rest, because it is safer and more useful, and because it helps to keep the others under. For example, the natural impulse of tenderness and warm attachment has been all over the world cultivated and strengthened to the highest possible pitch, because it is more grateful as a permanent stimulus, more compatible with human happiness and safety on the whole, and more capable of keeping dangerous passions under, than most other germs of human emotion. A particular form of the sentiment of manly pride has been sometimes chosen monarch of the passions for similar reasons; it being found capable of spreading a film of serene satisfaction over the life, and of maintaining a course of conduct safe for the individual and not hurtful to others. It is easy to conceive what would be the upshot if a like predominance were given to the fitful appetites of hunger and sex, to the passion of resentment, or even to the more paltry but very fascinating love of sporting excitement.
To play off one strong impulse against all the rest, and to strengthen it by exercise and by consecration, has been essential to the existence of every tribe of human beings that ever held together ; but this, though a highly conservative device and a great step in advance, can hardly be said to be philosophy. The nations of the civilised modern world, and many sects among the ancients, have recognised as the supreme guiding force of