The circulation of the blood was long since known; but the disposition of the vessels which conveyed the chyle to mix with it, and repair its losses; the existence of a gastric fluid which disposes the elements to the decomposition necessary to separate from organised matter, that portion which is proper to become assimilated with the living fluids; the changes undergone by the various parts and organs in the interval between conception and birth, and afterwards during the different ages of life; the distinction between the parts possessing sensibility and those in which irritability only resides, a property discovered by Haller, and common to almost every organic substance: these facts are the whole of what physiology has been enabled to discover, by indubitable observations, during this brilliant epoch; and these important truths may serve as an apology for the numerous explanations, mechanical, chemical, and organical, which have succeeded each other, and loaded this science with hypotheses destructive to its progress, and dangerous when used as the ground of medical practice. To the outline of the sciences we may add that of the arts, which, being founded upon them, have advanced with greater certainty, and broken the shackles of custom and common practice, which heretofore impeded their progress.

We may shew the influence which the progress of mechanics, of astronomy, of optics, and of the art of measuring time, has exercised on the art of constructing, moving, and directing vessels at sea. We may shew how greatly an increase of the number of observers, and a greater degree of accuracy in the astronomical determinations of positions, and in topographical methods, have at last produced an acquaintance with the surface of the globe, of which so little was known at the end of the last century.

How greatly the mechanic arts, properly so called, have given perfection to the processes of art in constructing instruments and machines in the practice of trade, and these last have no less added force to rational mechanism and philosophy. These arts are also greatly indebted to the employment of first movers already known, with less of expence and loss, as well as to the invention of new principles of motion.

We have beheld architecture extend its researches into the science of equilibriums and the theory of fluids, for the means of giving the most commodious and least expensive form to arches, without fear of altering their solidity; and to oppose against the effort of water a resistance computed with greater certainty; to direct the course of that fluid, and to employ it in canals with greater skill and success.

We have beheld the arts dependent on chymistry enriched with new processes; the ancient methods have been simplified, and cleared from useless or noxious substances, and from absurd or imperfect practices introduced from former rude trials; means have been invented to avert those frequently terrible dangers to which workmen were exposed. Thus it is that the application of science has secured to us more of riches and enjoyment, with much less of painful sacrifice or of regret.

In the mean time, chemistry, botany, and natural history, have very much enlightened the economical arts, and the culture of vegetables destined to supply our wants; such as the art of supporting, multiplying, and preserving domestic animals; the bringing their races to perfection, and meliorating their products; the art of preparing and preserving the productions of the earth, or those articles which are of animal product.

Surgery and pharmacy have become almost new arts, from the period when anatomy and chemistry have offered them more enlightened and more certain direction.

The art of medicine, for in its practice it must be considered as an art, is by this means delivered at least of its false theories, its pedantic jargon, its destructive course of practice, and the servile submission to the authority of men, or the doctrine of colleges; it is taught to depend only on experience. The means of this art have become multiplied, and their combination and application better known; and though it may be admitted that in some parts its progress is merely of a negative kind, that is to say, in the destruction of dangerous practices and hurtful prejudices, yet the new methods of studying chemical medicine, and of combining observations, give us reason to expect more real and certain advances.

We may endeavour more especially to trace that practice of genius in the sciences which at one time descends from an abstract and profound theory to learned and delicate applications; at another, simplifying its means, and proportioning them to its wants, concludes by spreading its advantages through the most ordinary practices; and at others again being rouzed by the wants of this same course of art, it plunges into the most remote speculations, in search of resources which the ordinary state of our knowledge must have refused.

We may remark that those declamations which are made against the utility of theories, even in the most simple arts, have never shewn any thing but the ignorance of the declaimers. We may prove that it is not to the profundity of these theories, but, on the contrary, to their imperfection, that we ought to attribute the inutility or unhappy effects of so many useless applications.

These observations will lead us to one general truth, that in all the arts the results of theory are necessarily modified in practice; that certain sources of inaccuracy exist, which are really inevitable, of which our aim should be to render the effect insensible, without indulging the chimerical hope of removing them; that a great number of data relative to our wants, our means, our time, and our expences which are necessarily overlooked in the theory, must enter into the relative problem of immediate and real practice; and that, lastly by introducing these requisites with that skill which truly constitutes the genius of the practical man, we may at the same time go beyond the narrow limits wherein prejudice against theory threatens to detain the arts, and prevent those errors into which an improper use of theory might lead us.

Those sciences which are remote from each other, cannot be extended without bringing them nearer, and forming points of contact between them.

The heavens are enriched for the man of science with new stars, and he applies his knowledge to determine and foretel with accuracy their positions and movements. Natural philosophy, gradually delivered from the vague explanations of Descartes, in the same manner as it before was disembarrassed from the absurdities of the schools, is now nothing more than the art of interrogating nature by experiment, for the parpose of afterwards deducing more general facts by computation.

The weight of the air is known and measured: it is known that the transmission of light is not instantancous; its velocity is determined, with the effects which must result from that velocity, as to the apparent position of the celestial bodies; and the decomposition of the solar rays into others of different refrangibility and colour. The rainbow is explained, and the methods of causing its colours to be produced or to disappear are subjected to calculation. Electricity, formerly considered as the property of certain substances only, is now known to be one of the most general phenomena in the universe. The cause of thunder is no longer a secret; Franklin has taught the artist to change its course, and direct it at pleasure. New instruments are employed to measure the variations of weight and humidity in the atmosphere, and the temperature of all bodies. A new science, under the name of meteorology, teaches us to know, and sometimes to foretel, the atmospheric appearances of which it will hereafter disclose to us the unknown laws.

While we present a sketch of these discoveries, we may remark how much the methods which have directed philosophers in their researches are simplified and brought to perfection; how greatly the art of making experiments, and of constructing instruments, has successively become more accurate; so that philosophy is not only enriched every day with new truths, but the truths already known have been more exactly ascertained; so that not only an immense mass of new facts have been observed and analysed, but the whole has been submitted in detail to methods of greater strictness.

Natural philosophy has been obliged to combat with the prejudices of the schools, and the attraction of general hypotheses, so seducing to indolence. Other obstacles retarded the progress of chemistry. It was imagined that this science ought to afford the secret of making gold, and that of rendering man immortal.

The effect of great interests, is to render man superstitious. It was not supposed that such promises, which flatter the two strongest passions of vulgar minds, and besides rouse that of acquiring glory, could be accomplished by ordinary means; and every thing which credulity or folly could ever invent of extravagance, seemed to unite in the minds of chemists.

But these chimeras gradually gave place to the mechanical philosophy of Descartes, which in its turn gave place to a chemistry truly experimental. The observation of those facts which accompany the mutual composition and decomposition of bodies, the research into the laws of these operations, with the analysis of substances into elements of greater simplicity, acquire a degree of precision and strictness ever increasing.

But to these advances of chemistry we must add others, which embrace the whole system of the science, and rather by extending the methods than immediately increasing the mass of truths, foretel and prepare a revolution of the happiest kind. Such has been the discovery of new means of confining and examining those elastic fluids, which formerly were suffered to escape; a discovery which, by permitting us to operate upon an entire class of new principles, and upon those already known, reduced to a state which escaped our researches, and by adding an element the more to almost every combination, has changed, as it were, the whole system of chemistry. Such has beenthe formation of a language, in which the names denoting substances sometimes express the resemblance or differences of those which have a common element, and sometimes the class to which they belong. To these advantages we may add the use of a scientific method, wherein these substances are represented by characters analytically combined, and moreover capable of expressing the most common operations and the general laws of affinity. And, again, this science is enriched by the use of all the means and all the instruments which philosophers have applied to compute with the utmost rigor the results of experiment; and lastly, by the application of the mathematics to the phenomena of chrystalization, and to the laws according to which the elements of certain bodies effect in their combination regular and constant forms.

Men who long had possessed no other knowledge than that of explaining by superstitious or philosophical reveries the formation of the earth, before they endeavoured to become acquainted with its parts, have at last perceived the necessity of studying with the most scrupulous attention the surface of the ground, the internal parts of the earth into which necessity has urged men to penetrate, the substances there found, their fortuitous or regular distribution, and the disposition of the masses they have formed by their union. They have learned to ascertain the effects of the slow and long continued action of the waters of the sea, of rivers, and the effect of volcanic fires; to distinguish those parts of the surface and exterior crust of the globe, of which the inequalities, disposition, and frequently the materials themselves, are the work of these agents; from the other portion of the surface, formed for the most part of heterogeneous substances, bearing the marks of more ancient revolutions by agents with which we are yet acquainted.

Minerals, vegetables, and animals are divided into various species, of which the individuals differ by insensible variations scarcely constant, or produced by causes purely local. Many of these species resemble each other by a greater or less number of common qualities, which serve to establish successive divisions regularly more and more extended. Naturalists have invented methods of classing the objects of science from determinate characters easily ascertained, the only means of avoiding confusion in the midst of this numberless multitude of individuals. These methods are, indeed, a real language, wherein each object is denoted by some of its most constant qualities, which, when known, are applicable to the discovery of the name which the article may bear in common language. These general languages, when well composed, likewise indicate, in each class of natural objects, the truly essential qualities which by their union cause a more or less perfect resemblance in the rest of their properties.

We have formerly seen the effects of that pride which magnifies in the eyes of men the objects of an exclusive study, and knowledge painfully acquired, which attaches to these methods an exaggerated degree of importance, and mistakes for science itself that which is nothing more than the dictionary and grammar of its real language. And so likewise, by a contrary excess, we have seen philosophers falsely degrade these same methods, and confound them with arbitrary nomenclatures, as futile and laborious compilations.

The chemical analysis of the substances in the three great kingdoms of nature; the description of their external form; the exposition of their physical qualities and usual properties; the history of the developement of organized bodies, animals, or plants; their nutrition and reproduction; the details of their organization; the anatomy of their various parts; the functions of each; the history of the manners of animals and their industry to procure food, defence, and habitation, or to seize their prey, or escape from their enemies; the societies of family or species which are formed amongst them; that great mass of truth to which we are led by meditating on the immense chain of organised beings; the relation which successive years produce from brute matter at the most feeble degree of organization, from organised matter to that which affords the first indications of sensibility and spontaneous motion; and from this station to that of man himself; the relation of all these beings with him, whether relative to his wants, the analogies which bring him nearer to them, or the differences by which he is separated: such is the sketch presented to the mind by modern natural history.

The physical man is himself the object of a separate science, anatomy, which, in its general acceptation, includes physiology. This science, which a superstitious respect for the dead had retardad, has taken advantage of the general disappearance of prejudice, and has happily opposed the interest of the preservation of man, which has secured it the patronage of men of eminence. Its progress has been such, that it seems in some sort to be at a stand, in the expectation of more perfect instruments and new methods. It is nearly reduced to seek in the comparative anatomy of the parts of animals and man, in the organs common to the different species, and the manner in which they exercise similar functions, those truths which the direct observation of the human frame appears to refuse. Almost every thing which the eye of the observer, assisted by the microscope, has been able to discover, is already ascertained. Anatomy appears to stand in need of experiments, so useful to the progress of other sciences; but the nature of its object deprives it of this means, so evidently necessary to its perfection.

The most singular, as well as the most excellent, of all his works, is that which is now the least read, and which is at the same time the most useful; I mean his "Novum Scientiarum Organum." This is the scaffold by means of which the edifice of the new philosophy has been reared; so that when the building was completed, the scaffold was no longer of any use. Chancellor Bacon was still unacquainted with nature, but he perfectly knew, and pointed out extraordinarily well, all the paths which lead to her recesses. He had very early despised what those square-capped fools teach in those dungeons called Colleges, under the name of philosophy, and did everything in his power that those bodies, instituted for the cultivation and perfection of the human understanding, might cease any longer to mar it, by their "quiddities," their "horrors of a vacuum," their "substantial forms," with the rest of that jargon which ignorance and a nonsensical jumble of religion had consecrated.

This great man is the father of experimental philosophy. It is true, wonderful discoveries had been made even before his time; the mariner's compass, the art of printing, that of engraving, the art of painting in oil, that of making glass, with the remarkably advantageous invention of restoring in some measure sight to the blind; that is, to old men, by means of spectacles; the secret of making gunpowder had, also, been discovered. They had gone in search of, discovered, and conquered a new world in another hemisphere. Who would not have thought that these sublime discoveries had been made by the greatest philosophers, and in times much more enlightened than ours? By no means; for all these astonishing revolutions happened in the ages of scholastic barbarity. Chance alone has brought forth almost all these inventions; it is even pretended that chance has had a great share in the discovery of America; at least, it has been believed that Christopher Columbus undertook this voyage on the faith of a captain of a ship who had been cast by a storm on one of the Caribbee islands. Be this as it will, men had learned to penetrate to the utmost limits of the habitable globe, and to destroy the most impregnable cities with an artificial thunder, much more terrible than the real; but they were still ignorant of the circulation of the blood, the weight and pressure of the air, the laws of motion, the doctrine of light and color, the number of the planets in our system, etc. And a man that was capable to maintain a thesis on the "Categories of Aristotle," the universale a parte rei, such-like nonsense, was considered as a prodigy.

The most wonderful and useful inventions are by no means those which do most honor to the human mind. And it is to a certain mechanical instinct, which exists in almost every man, that we owe far the greater part of the arts, and in no manner whatever to philosophy. The discovery of fire, the arts of making bread, of melting and working metals, of building houses, the invention of the shuttle, are infinitely more useful than printing and the compass; notwithstanding, all these were invented by men who were still in a state of barbarity. What astonishing things have the Greeks and Romans since done in mechanics? Yet men believed, in their time, that the heavens were of crystal, and the stars were so many small lamps, that sometimes fell into the sea; and one of their greatest philosophers, after many researches, had at length discovered that the stars were so many pebbles, that had flown off like sparks from the earth.

In a word, there was not a man who had any idea of experimental philosophy before Chancellor Bacon; and of an infinity of experiments which have been made since his time, there is hardly a single one which has not been pointed out in his book. He had even made a good number of them himself. He constructed several pneumatic machines, by which he discovered the elasticity of the air; he had long brooded over the discovery of its weight, and was even at times very near to catching it, when it was laid hold of by Torricelli. A short time after, experimental physics began to be cultivated in almost all parts of Europe. This was a hidden treasure, of which Bacon had some glimmerings, and which all the philosophers whom his promises had encouraged made their utmost efforts to lay open. We see in his book mention made in express terms of that new attraction of which Newton passes for the inventor. "We must inquire," said Bacon, "whether there be not a certain magnetic force, which operates reciprocally between the earth and other heavy bodies, between the moon and the ocean, between the planets, etc." In another place he says: "Either heavy bodies are impelled toward the centre of the earth, or they are mutually attracted by it; in this latter case it is evident that the nearer falling bodies approach the earth, the more forcibly are they attracted by it. We must try," continues he, "whether the same pendulum clock goes faster on the top of a mountain, or at the bottom of a mine. If the force of the weight diminishes on the mountain, and increases in the mine, it is probably the earth has a real attracting quality."

We should remember that there was once a discipline called natural philosophy. Unfortunately, this discipline seems not to exist today. It has been renamed science, but science of today is in danger of losing much of the natural philosophy aspect.

241b 34 Every moving thing must be moved by something. For if it does not have the source of its motion in itself, it is clear that it is moved by something else (for another 40 thing will be the mover); but if it is in itself, let AB be taken, which is moving in its own right, and not by means of some part of it being moved. First, then, to suppose that AB is moved by itself since the whole is moved and by nothing outside it,would be as if, when KL was moving LM and was itself moving, one were to say that KM was not moved by anything, 242a, 35 on account Of its not being evident what was the mover and what the moved. Then too, what is not moved by anything need not stop moving because something else is at rest, but if something is at rest because something else has stopped moving, it must be moved by something. If this is taken as given, then every moving thing will be moved by something. 40 For since AB has been assumed to be moving, it must be divisible. since every moving thing is divisible. Then let it have been divided at C.Then if CB is not moving, AB will not be moving, for if it were moving, it is clear that AC would be moving while CB was at rest. But we have agreed that what is at rest when something is not moving is moved by something, so that necessarily every moving thing is moved by something, since the moving thing will always be divisible, and when the part is not moving the whole too must be at rest.

50 And since every y moving thing must be moved by something, if something is moved with a motion in place by another moving thing, and the thing moving it is moved in turn by another moving thing, and that one by another, and so on always, it is necessary that there be become infinite. So let A be moved by B, B by C, C by D, and always he next by a next. Then since it is set down that the mover causes motion by moving, the motions of the mover 60 and the moved must happen at the same time (since at the same time the mover moves and the moved is moved); it is clear then that at the same time there will be motion of A and of B and of C and of each of the things causing g motion and being moved. Then let the motion of each be taken, and let that of A be E that of B be F, and those of C and D be G and H. For though each is always moved by another, still there will be a motion of each to be taken that is one in number; for every motion is from something to something, and not infinite at its extremities. And by a motion one in number, I mean one that takes place from something that is numerically the same, to something numerically the same, in a time that is numerically the same. For It is possible for a motion to be the same in genus, in 242b, 35 species, or in number: in genus, those in the same category of being, such as changes of thinghood or of quality; in species, those from something the same in kind to something the same in kind, such as from white to black or from good to bad of a nondiffering kind; but in number, that 40 from something one in number to something one in number, in the same time, such as from this white to this black, or from this place to that one, in this time, since if it were in a different time, it would no longer be a motion one in number, but one in species. But these things were spoken about in what went before [V, 4].