Popular Science Monthly/Volume 33/August 1888/The Unity of Science

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ONE of the greatest anatomists of the age and a distinguished jurist were sitting together at the festival of a German university. They were engaged in a friendly discussion as to which of them should, by virtue of his profession, be best known to the world. At last the lawyer surrendered his claim, remarking that the arteries and muscles were the same in America and Europe, while it was doubtful if the ideas of the Roman law enjoyed a like extension. But I do not believe that the illustrious naturalist felt any great joy in the victory he had obtained; for both professors were brave defenders of the universality of science in the highest sense of the word, and were certainly not expressing their most serious thoughts in this moment of by-play. How much, during the half-century that has passed since this conversation, the feeling of the unity of science has advanced, and to how great a degree it has entered into the intimate convictions of the most learned men, does not need to be told.

At a time when all students are avowing themselves bonded in the universality of science, the speaker who is called upon to discuss the subject finds himself in the face of an audience whom he has nothing to teach, but from whom he has much to learn.

A natural inclination leads him to consult, first, the biologists, who have probed to the earliest manifestations of life on our planet; and he is seized with wonder at finding that paleontology, emancipated from the curious contemplation of extinct organisms, has risen to phylogeny, and is following in the host of vital forms that order of evolutionary succession which causes the most recent beings to be regarded as the descendants and heirs of their predecessors. Biological paleontology judges the law of successive evolution to be immanent in the development of species and of individuals. It discovers that the development of the most perfect beings on the earth is made after the form of the generations which preceded those elevated organisms, in such a way that every example of ontogenic evolution appears to be a rapid summary of the phylogenic evolution that preceded the appearance of the being the embryology of which is studied.

Every organized form is fitted in as an essential link in a chain of derivation and descent. Nothing is now left of that fancy that saw in the plan of Nature a mass of accidental variations, like the caprice of an author who published at the same time with his finished works all of his rough draughts and printers' proofs.

At the point we have reached, natural history, regarded as biogeny, can not do without paleontology. Zoölogy affirms that there ought to be transitional forms between reptiles and birds, which present many points of contact and traits of fundamental analogy; but such forms are not found among the beings of our age. Paleontology, however, shows that in the secondary or mesozoic age there lived reptiles having the form of birds, and birds having the form of reptiles.

Just as the paleontologist has taken his place among biologists by investigating the characters of successive developments and discovering and reconstructing the relationships of extinct organisms, so the archaeologist has, through ethnography and ethnology, without perceiving it, entered the same camp.

It is the same with whatever relates to civilization. Sometimes the parts are reversed. The linguist asks the physiologist to investigate the laws of phonation and to study accents, analyze the quality of the sound of the vowels, and the sounds that correspond with each consonant, among different races and in different provinces and cities; while the physiologist insensibly acquires the skill and erudition of the philologist.

For a long time doctors believed that they had included all the causes of disease in virulent matters, the inclemencies of the atmosphere, abuses of strength and pleasures, and indulgences of passion. The part of parasites was regarded as limited and secondary, and of those, animal parasites were regarded as the most important, while vegetable parasites were not supposed to play any appreciable part. During the former half of this century, the most intelligent persons considered botany as a part of natural history, very fit to discipline the senses and strengthen the understanding of the future doctor, to cultivate the spirit of observation within him, and to exercise him in the construction of syntheses which would permit him to classify the phenomena. The study of botany was valued only as a gymnastics of the intelligence. It was often forgotten after the first years of study, unless it was modestly called to mind to illustrate the difference between one medicinal plant and another, as parsley and hemlock, or a poisonous and edible mushroom. Now, behold the whole camp of etiologists and a good part of the camp of anatomo-pathologists pressing into the minute examination of the lowest plants, most of them belonging to the group of those microscopic fungi which are divided transversely and owe to that division an extremely rapid increase. These fungi are called, on account of the division which they undergo, schizomycetes. In many maladies, and those of the most grave, one of these species of fungus is considered the determining cause of the disease. The schizomycetes are the invisible enemies of the health of man. The chief defense against them is indirect; it consists in taking care that they do not, through hygienic deficiencies, find in the body of man a fertile soil predisposed to receive and feed them. Hence these invisible enemies have forced the doctor to interest himself in botany, if only to convince himself that the presence of a noxious fungus does not inevitably imply a sentence of death. Botany, therefore, is not only an exercise in education and an auxiliary to medicine, but it is also an integral part of medicine and a fertile source of explanations. The unity of botany and medicine is in appearance only on the ground of the infinitely little; but the economy of all organized nature is really displayed in it, the cycle of life which includes death—death from which life, the true phoenix, perpetually rises again.

Physics has higher ambitions. Mother of all the sciences, including metaphysics, and ever young in its indefatigable research, it unites the efforts of a matured experience with those of a legitimate boldness. It takes pity on the despair of the chemist who can not catch in his crucible a piece of the glowing shell of the stars, and teaches him how to make use of a ray of light to discover the nature of those distant substances, and to make sure that they are the same in the celestial bodies as they are in the terrestrial globe, which is also celestial in its turn.

It is not satisfied with overcoming the obstacle of distance, which seems to be insurmountable. If to economize time is the most effective way of enriching men and states, physics has the best right to aspire to the glory of being the peerless servant of all administrations, both of public and private affairs. The physiologist also has physics to thank for giving him the means, through the decomposition of light, of perceiving in an instant whether the coloring-matter of the blood is more or less oxidized, while chemical analysis can make it clear only after long and difficult experiments.

But, while different sciences assist one another by reciprocally facilitating, checking, and perfecting each other's work, there is one that has a superior part, at once foundation and summit, elementary and transcendent. This science is the base of all the others, and distributes to the most positive of its sisters crowns, the precious stones of which are touchstones. All of my learned hearers will divine that I am speaking of mathematics, the Dutch name of which (Wiskunde) signifies the science of the certain, the positive science, absolutely science. This science guides our first steps in the highway of thought; it is so blended with the premises of every deduction, that its truths, accepted by the ages, seem to have imposed themselves as axioms, or theses a priori innate to the faculty which we call intelligence, and thereby independent of all demonstration. Now, this hypothesis, widely prevailing as it may be (and it is as universal as the belief that the sun rises), the psychologist shows to be erroneous.[2]

The possibility even of error proves the initiative which we take in the formation of these axioms. They are merely the summary of our first and quite simple observations—a summary which has taken the mathematical form, and seems, under that form, to approach the absolute. It is mathematics which, in all the sciences of observation, conducts to the most precise conclusions, whether it is employed in representing in figures the arrangement of the leaves of a plant, or in formulating the law of gravitation, or the law of the enfeeblement of sound and light in the ratio of the square of the distance. It is mathematics that points out perturbations, and imposes limits upon physical laws. It is mathematics that serves to direct the intelligence, whether by showing it how to correct an error of observation, such as Newton had to contend against when he was inquiring if the law of gravitation was applicable to the motions of the moon, or by helping it to ascertain that not all the causes on which a phenomenon depends have been included in a formula to which the facts refuse to adapt themselves. In short, mathematics is a beacon-light and a means of verification. It inspires all the more confidence because it is the only science that has never had to change its direction, from Euclid to Galileo, from Newton and Huygens to Laplace and Lagrange.

It gives form as well as foundation to knowledge. No draughtsman can hold a contest with graphic geometry in any question of figuring the relations of different phenomena that are functions of one another.

Mathematics is the draughtsman of thought. The beauty of the formulas by which it has been the prophetic guide for the other sciences can not be forgotten; as in the discovery, for example, of the series of homologous compounds by which chemistry has been so greatly enriched. This science, which has produced so quick a revolution in the conscience, force, and art of life, owes to mathematics the concept of valences, and consequently the knowledge of the mechanism of substitutions, the variations of which are so infinite as to belie the maxim, "There is nothing new under the sun."

It is mathematics that renders the honors of positive knowledge to ancient times, in that period which, besides having become classic for its art, also laid the foundations of science, and made the Greeks masters of the true as well as of the beautiful; whether with Pythagoras, Euclid, and Archimedes it established the bases of geometry and mechanics, with Aristotle founded natural history, with Hippocrates introduced the art of observing and questioning, or with Plato made the method of discussion an art of reflecting ideas in the mirror of facts.

Hence, the person who sees only labor lost in philosophical researches, is in error. Philosophy (I am speaking of speculative philosophy) has not gone on a journey from which it has not returned, but, having traversed heaven and earth with vigorous will, has come back to tell that it has not succeeded with its a priori theories in solving the problems which impose themselves upon all thinking men. That is the confession which Dr. Faust makes when, after having studied all the sciences, he realizes that no one can attain knowledge without plunging into the reality of life. Yet we do not believe that philosophy has forfeited the glory that is due to every sincere effort, in whatever order of research. It was necessary, indispensable, and certain, that reason, escaping the limits of things, should exhaust itself in tentatives. Did not Plato of necessity create Aristotle, and stoicism Lucretius, in the same way that Bacon and Descartes, Galileo and Kant, were born of scholastic and dogmatic thought?

Philosophy (I am not speaking of speculative philosophy this time) now comprehends that it can aspire to fill only two missions: to be the synthesis of all our knowledge, and to generalize the method which ascends from facts to ideas, persuaded that the idea springs from the fact and does not create it. In this sense philosophy, suffering modifications as time goes on, will be always the synthesis of the known (not of the knowable), and, freed from that which is of speculation and ideology, will remain the guardian mistress of the harmony in which the true, the beautiful, and the good are to be blended.

Thus there remains a task for philosophy that peculiarly belongs to it—one of the noblest tasks—to examine the solidity of the bases of morals, independently of customs and the prejudices of individual nations and times; and ethics is not separable from aesthetics. So understood, philosophy is the science of sciences, or absolutely the science, the guarantee of progress, the guardian of morals, the mediator between science and art, the supreme expression of liberty of thought which admits neither innate ideas nor revelation. We comprehend everything under the ægis of such a philosophy, precisely because method has become single.

The long-cherished contrast between the positive and historical sciences has disappeared, for we are persuaded that the point of departure in this also is observation, that the continuity of facts must be followed step by step in seeking out the law, in tracing the concatenation, in order to rise to the conception that all has become what it was necessary for it to become. Harmony in the universe is inherent to the beginning of things; and if we could embrace them in a single glance we should see that first causes correspond with final causes; and teleology and causality would be merely the two faces of the same medal.

Unity of method conduces to the union of the exact sciences and of historical investigations, of jurisprudence and anthropology, of biology and military art, of politics and statistics. From this marriage have been born the social sciences, which have come to demonstrate that society has its evolution, its exigencies, its diseases, and, in short, its laws like the individual, and that it is necessary to calculate facts and observe their march in order to be able to act-upon the influences on which, that march depends and by which it is regulated.

The objective of the social sciences is to neglect no factor of life. It is only by a ponderous and progressive labor that can be realized that amelioration of the social conditions which can never be attained by a sudden leap, but which we can see in fact preparing and asserting itself by a gradual and continuous evolution.

The evolution of mechanics, of which the strongest, most adroit, and most expeditious workman is electricity, is daily reducing the muscular labor of man. By virtue of the principle of the conservation of energy, the diminution of muscular labor is of advantage to intellectual labor, in quantity as well as in intensity. Attention becomes more profound, intelligence more quick, judgment more sure. The danger of the workman of modern times becoming brutalized is, without any doubt, greatly diminished. The workman has become more polite, more reflective, and more human, and is advancing further every day toward the conquest of the more considerable place in society which he merits. Not only the quantity of intellectual labor has been advanced by the technical applications which science has made possible; we have a right to ask also if its quality has not gained still more.

The telegraph and the telephone have made all the world more expeditious, more attentive, more ready in its judgments, and more prompt in its decisions. Recollect the perplexity into which, thirty years ago, a letter demanding prompt advice or immediate assistance would put us. Knowing that we had time, that we should have to wait several hours before sending an answer or beginning a journey, we gave ourselves up to doubts; and, when doubt possesses itself of a man, his judgment is often obscured and his will paralyzed. Now that we have to leap the ditch, to think on the instant, and turn our good-will at once into action, thought takes wings, and our decision is resolute and bold.

In this way Volta and Galvani have become powerful educators. By their scientific discoveries they are teaching our sons to think readily, to will firmly, and to express themselves briefly, in a manner precise and conformed to their thought. A rapid physical means of communication triumphs over torpor of the intelligence, indecision of character, and prolixity in speech. Further, this electric pile has become the mother of the postal-card, another mistress of simple and pertinent words. The later generations know so well how to use these instruments that to some the postal-card is already too large. In a very few lines they can assure friends of continued affection and produce the illusion that one is for an instant enjoying their presence, feeling their caresses, and experiencing the stimulation of their spirit. Economy of time leaves leisure to write short letters, for which there was not time in Pliny's day; and the exchange of thought has gained as immensely as the exchange of friendly sentiments. In this way it is a fact that every application of science develops the moral force of man.

Man measures the universe, and he measures himself in the rapidity of his thought and will, and finds the relation between the world and himself. He knows that he measures with relation to himself, that he measures with his senses; and in the relations between them and the world, in the necessary relation which unites them, he finds the human absolute. Reducing all the measures to a single scale, he discovers the unity of the science for which there exists a law that embraces all, anthropology. Anthropology examines the nature of man, the civilization of man, his laws, his errors, his poetry, his ideal. This ideal, which must go on ascending in proportion as man attains knowledge of himself, consists in the harmonious development of the species; and this embraces all the factors—the functions, passions, and aspirations—of his moral being. The more the individual assimilates himself to it, the more this harmony makes of man a work of art, the more it gives him the faculty and the right to admire and love his title of man; because he finds the reason of the good and the beautiful rooted in his nature. Anthropology embraces ethics, æsthetics, and history.

Hope comes to fortify the ideal at an epoch when we are comprehending the transformation of force and of form; because, with this conception of the conservation of force, all phenomena and all the moral manifestations of men may perfect themselves without ever striking upon an ultimate limit. Against such an ideal, against such a hope, the shadows of ignorance and the discouragements of pessimism will never prevail. The shadows are afraid of a statue,[3] and pessimism has no courage but that of despair. But the poet (Victor Hugo) has said with right, "Whoever despairs is in the wrong." He who does not despair and who works carries in his own conscience the fruit and the recompense of his efforts.—Translated for the Popular Science Monthly from the Revue Scientifique.

Prof. Prestwich, in a paper on the date, duration, and general conditions of the last glacial period, estimates the date of the melting of the ice-sheet at from eight to ten thousand years ago. He admits the appearance of man in Europe before the spread of the ice over the continent, and assigns the residence of neolithic man in Europe—although he had probably been established in the East before that date—to some three or four thousand years b. c.
  1. Address at the reopening of the University of Rome, November 3, 1887.
  2. Moleschott says, in his "Der Kreislauf des Lebens": "We yet teach children that they can reach the highest summits of thought, without any aid from the senses, by starting from certain premises which they have brought with them at birth as an integral part of their intellect, and for the knowledge of which they have only to appeal to their memory. The mathematician calls these premises axioms, and he persuades children as well as men, when he submits them to them, as, for instance, that the whole is greater than a part, and that the whole is equal to the sum of its parts. And yet no child knows it until he has seen, say a hundred times, that an apple disappears when it is cut into four pieces and these pieces are divided among four persons." See also Helmholtz, "Ueber den Ursprung und die Bedeutung der geometrlschen Axiome" ("On the Origin and Signification of the Geometrical Axioms").
  3. I mean the statue of Giordano Bruno. The place selected for its site (also a very natural location, and the only one worthy of it), the Campo del Fiori, where it looks upon the spot where the heroic thinker was burned, is a protest against clerical intolerance.