History Of Science

"Towards the latter half of the eighteenth century clearer views began to be held concerning the relations of atmospheric air to the phenomena of combustion and of calcination; many half-forgotten facts relating to these phenomena were recalled, and the inconsistencies and insufficiency of phlogiston as a dogma became gradually manifest. Three cardinal facts conspired to bring about its overthrow—the isolation of oxygen by Priestley; the recognition by him of the nature of atmospheric air, and of the fact that one of its constituents is oxygen; and, lastly, the discovery by Cavendish that water is a compound, and that its constituents are oxygen and . The significance of these facts was first clearly grasped by Lavoisier, and to him is due the credit of their true interpretation. By reasoning and experiment he proved conclusively that all ordinary phenomena of burning are so many instances of the combination of the oxygen of the air with the combustible substance; that calcination is a process of combination of the oxygen in the air with the metal, which thereby increases in weight by the amount of oxygen combined. Water no longer a simple substance is formed by the union, weight for weight, of oxygen and hydrogen. ...The phlogiston myth was thus exploded."

"One of the most fundamental principles of Lavoisier's chemistry was the use of numbers, notably in relation to what we often call today the principle of ... The principle implies that the experimenter must not only keep account of all the reacting solids and liquids, but also the gases—that is, all of the products. ...This rule led to quantitative experiments. Lavoisier was not the first person to use numbers in chemistry but he was a pioneer in using such numerical measurements as the basis of his system of chemistry. ...When Lavoisier first announced this law, chemists generally believed in... "phlogiston" which supposedly entered into chemical reactions (such as combustion) but had no weight. It was a radical step, therefore, for Lavoisier to base a system of chemistry on a balance of weights and to maintain that chemistry is not concerned with weightless "substances." ...this was indeed a chemical revolution."

"Intelligent design... is not a scientific argument at all, but a religious one. It might be worth discussing in a class on the history of ideas, in a philosophy class on popular logical fallacies, or in a comparative religion class on origin myths from around the world. But it no more belongs in a biology class than alchemy belongs in a chemistry class, phlogiston in a physics class or the stork theory in a sex education class. In those cases, the demand for equal time for "both theories" would be ludicrous. Similarly, in a class on 20th-century European history, who would demand equal time for the theory that the Holocaust never happened?"

"My thesis, paradoxically, and a little provocatively, but nonetheless genuinely, is simply this:PROBABILITY DOES NOT EXIST.The abandonment of superstitious beliefs about the existence of Phlogiston, the Cosmic Ether, Absolute Space and Time, ... , or Fairies and Witches, was an essential step along the road to scientific thinking. Probability, too, if regarded as something endowed with some kind of objective existence, is no less a misleading misconception, an illusory attempt to exteriorize or materialize our true probabilistic beliefs."

"From inflammable air and dephlogisticated air water is produced."

"Now Mayow, like Boyle, conceived the air as made up of minute particles, while he restricted himself to two varieties, those, namely, which are necessary to life, called by him "spiritus igno-aereus," and those incapable of supporting respiration or combustion, which are left after the removal of this "spiritus." Since a mixture of saltpetre and sulphur continued burning even under water, he assumed that his igno-aereal particles must also be contained in the salt. Acids too contained the new principle. ...Mayow died in 1679 at the age of thirty-four years; had he lived but a little longer, it can scarcely be doubted that he would have forestalled the revolutionary work of Lavoisier, and stifled the theory of phlogiston at its birth. As it was, his work, though rendered in one of the most luminous and convincing scientific publications of the period, was immediately forgotten, and so proved of little effect on the evolution of our modern chemical system."

"Some hold that fundamental ideas have changed so often within science—especially within physics—that we should always expect our current views to turn out to be wrong. Sometimes this argument is called the “pessimistic meta-induction.” The prefix “meta” is misleading here, because the argument is not an induction about inductions; it’s more like an induction about explanatory inferences. So let’s call it "the pessimistic induction from the history of science." The pessimists give long lists of previously posited theoretical entities like phlogiston and caloric that we now think do not exist... Optimists reply with long lists of theoretical entities that once were questionable but which we now think definitely do exist—like atoms, germs, and genes."

"If I were giving this lecture fifty years from now, the word "gravitation" would be as old-fashioned as the word "phlogiston" is to us. Relativity has certainly demoted gravitation as a real explanation, just as Priestley's and Lavoisier's analyses and decoding of chemical reactions destroyed the word "phlogiston.""

"Lacan goes wrong by relying (quite uncritically!) on Saussure's signifier-signified conception of language. It is understandable that Lacan, when he began to write in the 1930s, should learn Saussure's turn-of-the-century linguistics. But even at the end of his life he and now his followers write about signifiers and signifieds as though the Chomskyan revolution in linguistics had never happened. Contemporary literary theorists tirelessly quote Saussure. But why? Today's linguists no more use Saussure's model than today's physicists use the concept of phlogiston. ...My point is not that Chomsky is right but that Saussure and Lacan are wrong."

"Inspired by Lavoisier, a small band of French chemists Berthollet, Fourcroy, Guyton de Morveau thereupon set to work to remodel the system of chemistry and to recast its nomenclature so as to eliminate all reference to phlogiston. The very names "oxygen," "hydrogen," "nitrogen," corresponding respectively to the "dephlogisticated air," "phlogiston," and "phlogisticated air" of Priestley, were coined by the new French school."

"When Priestley described his discovery... he introduced... an open admission of the role of randomness in his work—even including a subtle dig at the theoretical, synthetic mode of Newton and his followers:More is owing to what we call chance... to the observation of events arising from unknown causes, than to any proper design, or preconceived theory in this business. ......But ...Priestley himself was trapped in a preconceived theory ...almost entirely unfounded, though he clung to it for the rest of his life. ...Priestley seared it directly into the name he gave his pure air: dephlogisticated air. That awkward name came from the closest thing to a dominant research paradigm in... : the phlogiston theory, one of the all-time classics in the history of human error."

"For a time le principe oxygine was regarded by this school in much the same relation as phlogiston was regarded by Stahl and his followers. The one fetich was exchanged for the other. The combustible principle—phlogiston—was renounced for the acidifying principle—oxygen. The new chemistry for a time centred itself round oxygen, just as the old chemistry had centred itself round phlogiston. The views of the French school met with no immediate acceptance in Germany, the home of phlogistonism, or in Sweden or England, possibly owing, to some extent, to national prejudices. The spirit of revolution, even although it might be an intellectual revolution, had not extended to these countries. Priestley, Cavendish, and Scheele could not be induced to accept the new doctrine. It was, however, accepted by Black, and its principles taught by him in Edinburgh; and before the end of the century it had practically supplanted phlogistonism in this country. Some of those who, like Kirwan, had energetically opposed the new theory ended by enthusiastically embracing it. Its introduction into Germany was mainly due to the influence of Klaproth."

"Long before it became a scientific aspiration to estimate the age of the earth, many elaborate systems of the world chronology had been devised by the sages of antiquity. The most remarkable of these occult time-scales is that of the ancient Hindus, whose astonishing concept of the Earth's duration has been traced back to Manusmriti, a sacred book."

"Religious faith in the case of Hindus has never been allowed to run counter to scientific laws; moreover the former is never made a condition for the knowledge they teach, but they are always scrupulously careful to take into consideration the possibility that by reason both the agnostic and atheist may attain truth in their own ways."

"...In manufacture, India was the first to make cotton and purple [dye], it was proficient in all works of jewelry, and the very word 'sugar', as well as the article itself, is the product of India. Lastly she has invented the game of chess and the cards and the dice."

"The Hindus no less than the Greeks have shared in the work of constructing scientific concepts and methods in the investigation of physical phenomena , as well as of building up a body of positive knowledge which has been applied to industrial technique; and Hindu scientific ideas and methodology (e.g. the inductive method or methods of algebraic analysis) have deeply influenced the course of natural philosophy in Asia—in the East as well as the West—in China and Japan, as well as in the Saracen empire."

"The conclusions of modern science are the very conclusions the Vedanta reached ages ago; only in modern science they are written in the language of matter. Today we find wonderful discoveries of modern science coming upon us like bolts from the blue, opening our eyes to marvels we never dreamt of. But many of these are only re-discoveries of what had been found ages ago. ... All science is bound to this conclusion in the long run. Manifestation, and not creation, is the word of science today, and the Hindu is only glad that what he has been cherishing in his bosom for ages is going to be taught in more forcible language, and with further light from the latest conclusions of science."

"After these conversations with Tagore some of the ideas that had seemed so crazy suddenly made much more sense. That was a great help for me."

"In the West they learnt from Plato and Aristotle and in India “Arab scholars sat at the feet of Buddhist monks and Brahman Pandits to learn philosophy, astronomy, mathematics, medicine, chemistry and other subjects.” Caliph Mansur’s (754-76) zeal for learning attracted many Hindu scholars to the Abbasid court. A deputation of Sindhi representatives in 771 C.E. presented many treatises to the Caliph and the Brahma Siddhanta of Brahmagupta and his Khanda-Khadyaka, works on the science of astronomy, were translated by Ibrahim al-Fazari into Arabic with the help of Indian scholars in Baghdad. The Barmak (originally Buddhist Pramukh) family of ministers who had been converted to Islam and served under the Khilafat of Harun-ur-Rashid (786-808 C.E.) sent Muslim scholars to India and welcomed Hindu scholars to Baghdad. Once when Caliph Harun-ur-Rashid suffered from a serious disease which baffled his physicians, he called for an Indian physician, Manka (Manikya), who cured him. Manka settled at Baghdad, was attached to the hospital of the Barmaks, and translated several books from Sanskrit into Persian and Arabic. Many Indian physicians like Ibn Dhan and Salih, reputed to be descendants of Dhanapti and Bhola respectively, were superintendents of hospitals at Baghdad. Indian medical works of Charak, Sushruta, the Ashtangahrdaya, the Nidana, the Siddhayoga, and other works on diseases of women, poisons and their antidotes, drugs, intoxicants, nervous diseases etc. were translated into Pahlavi and Arabic during the Abbasid Caliphate. Such works helped the Muslims in extending their knowledge about numerals and medicine."

"Indian students should value their religious culture and of course, the classical Indian culture bears importantly on the meaning of life and values. I would not separate the two. To separate science and Indian culture would be harmful … I don’t think it is practical to keep scientific and spiritual culture separate."

"Although it would seem as if we had already furnished sufficient proofs that modern science has little or no reason to boast of originality, yet before closing this volume we will adduce a few more to place the matter beyond doubt... In the famous and recent work of Christna et le Christ, we find the following tabulation: [...]"Mathematics.--They invented the decimal system, algebra, the differential, integral, and infinitesimal calculi. They also discovered geometry and trigonometry, and in these two sciences they constructed and proved theorems which were only discovered in Europe as late as the seventeenth and eighteenth centuries[...] [...]"Chemistry.--They knew the composition of water, and formulated for gases the famous law, which we know only from yesterday, that the volumes of gas are in inverse ratio to the pressures that they support. They knew how to prepare sulphuric, nitric, and muriatic acids; the oxides of copper, iron, lead, tin, and zinc; the sulphurets of iron, copper, mercury, antimony, and arsenic; the sulphates of zinc and iron; the carbonates of iron, lead, and soda; nitrate of silver; and powder. "Medicine.--Their knowledge was truly astonishing. In Tcharaka and Sousruta, the two princes of Hindu medicine, is laid down the system which Hippocrates appropriated later. Sousruta notably enunciates the principles of preventive medicine or hygiene, which he places much above curative medicine--too often, according to him, empyrical. Are we more advanced to-day? It is not without interest to remark that the Arab physicians, who enjoyed a merited celebrity in the middle ages--Averroes among others--constantly spoke of the Hindu physicians, and regarded them as the initiators of the Greeks and themselves. [...]"Surgery.--In this they are not less remarkable. They made the operation for the stone, succeeded admirably in the operation for cataract, and the extraction of the foetus, of which all the unusual or dangerous cases are described by Tcharaka with an extraordinary scientific accuracy. [...]"Architecture.--They seem to have exhausted all that the genius of man is capable of conceiving. Domes, inexpressibly bold; tapering cupolas; minarets, with marble lace; Gothic towers; Greek hemicycles; polychrome style--all kinds and all epochs are there, betokening the origin and date of the different colonies, which, in emigrating, carried with them their souvenirs of their native art." Such were the results attained by this ancient and imposing Brahmanical civilization.... Beside the discoverers of geometry and algebra, the constructors of human speech, the parents of philosophy, the primal expounders of religion, the adepts in psychological and physical science, how even the greatest of our biologists and theologians seem dwarfed! Name to us any modern discovery, and we venture to say, that Indian history need not long be searched before the prototype will be found of record."

"We catch a glimpse of the great river of science which never ceases to flow in India. For India has carried and scattered the data of intellectual progress for the whole world, ever since the pre-Buddhist period when she produced the Sankhya philosophy and the atomic theory."

"The skill of the Indian in the production of delicate woven fabrics ... in all manner of technical arts has from very early times enjoyed worldwide celebrity."

"In the time of Alexander, says Garrison, "Hindu physicians and surgeons enjoyed a well-deserved reputation for superior knowledge and skill," and even Aristotle is believed by some students to have been indebted to them."

"In order to instill a proper and well-founded pride in Hindus, it is (once more) most important to restore the truth about Hindu history, especially about Hindu society's glorious achievements. In technology, it cannot match China, which was the world leader until a mere three, four centuries ago. But in abstract sciences like linguistics, logic, mathematics, Hindu culture has been the chief pioneer. In psychology, it is still unsurpassed, though this is not yet fully recognized in the West, the part of the world that still arbitrates on what can count as rational and scientific."

"In the Vedic Age, India was very religious, but it was also ahead of the rest in mathematics and astronomy. Thus, the geometry of the Shulba Sutras, geometrical appendices to the manuals of ritual (Shrauta Sutras), include the oldest known formulation of the theorem named after Pythagoras, developed in the context of Vedic altar-building. Modern Hindus are fond of recalling this scientific element in their tradition, e.g. by quoting Carl Sagan: “Hindu cosmology gives a time-scale for the earth and the universe which is consonant with that of modern scientific cosmology”, as opposed to the limited Biblical-Quranic cosmology, which was protected against more far-sighted alternatives by a vigilant religious orthodoxy."

"Fakhr-i-Mudabbir gives primacy to the bow and the sword as the most effective weapons of the horseman. Both these weapons were of different varieties. Among them all, the Hindu sword was the best and most lustrous (gawhardartar). Their export to such distant areas as Ummayad Spain and Seljuq Anatolia too is attested. He also declares that there is no better lance than the Indian."

"Sushruta described many surgical operations cataract, hernia, lithotomy, Caesarian section, etc. and 121 surgical instruments, including lancets, sounds, forceps, catheters, and rectal and vaginal speculums. Despite Brahmanical prohibitions he advocated the dissection of dead bodies as indispensable in the training of surgeons. He was the first to graft upon a torn ear portions of skin taken from another part of the body; and from him and his Hindu successors rhinoplasty the surgical reconstruction of the nose descended into modern medicine. "The ancient Hindus," says Garrison, "performed almost every major opera- tion except ligation of the arteries.""

"Chemistry developed from two sources—medicine and industry. Something has been said about the chemical excellence of cast iron in ancient India, and about the high industrial development of Gupta times, when India was looked to, even by Imperial Rome, as the most skilled of the nations in such chemical industries as dyeing, tanning, soap-making, glass and cement. As early as the second century B.C. Nagarjuna devoted an entire volume to mercury. By the sixth century the Hindus were far ahead of Europe in industrial chemistry; they were masters of calcination, distillation, sublimation, steaming, fixation, the production of light without heat, the mixing of anesthetic and soporific powders, and the preparation of metallic salts, compounds and alloys. The tempering of steel was brought in ancient India to a perfection unknown in Europe till our own times; King Porus is said to have selected, as a specially valuable gift for Alexander, not gold or silver, but thirty pounds of steel.22 The Moslems took much of this Hindu chemical science and industry to the Near East and Europe; the secret of manufacturing “Damascus” blades, for example, was taken by the Arabs from the Persians, and by the Persians from India."

"The Hindus seem to have been the first people to mine gold.... Much of the gold used in the Persian Empire in the fifth century before Christ came from India. Silver, copper, lead, tin, zinc and iron were also mined-iron as early as 1500 B.C. U The art of tempering and casting iron developed in India long before its known appearance in Europe; Vikramaditya, for example, erected at Delhi (ca. 380 A.D.) an iron pillar that stands untarnished today after fifteen centuries; and the quality of metal, or manner of treatment, which has preserved it from rust or decay is still a mystery to modern metallurgical science." Before the European invasion the smelting of iron in small char- coal furnaces was one of the major industries of India. The Industrial Revolution taught Europe how to carry out these processes more cheaply on a larger scale, and the Indian industry died under the competition... Europe looked upon the Hindus as experts in almost every line of manufacture—wood-work, ivory-work, metal-work, bleaching, dyeing, tanning, soap-making, glass-blowing, gunpowder, fireworks, cement, etc.21 China imported eyeglasses from India in 1260 A.D."

"It is India that gave us the ingenious method of expressing all numbers by ten symbols, each receiving a value of position as well as an absolute value; a profound and important idea which appears so simple to us now that we ignore its true merit."

"The Hindus were not so successful in geometry. In the measurement and construction of altars the priests formulated the Pythagorean theorem (by which the square of the hypotenuse of a right-angled triangle equals the sum of the squares of the other sides) several hundred years before the birth of Christ. Aryabhata, probably influenced by the Greeks, found the area of a triangle, a trapezium and a circle, and calculated the value of π (the relation of diameter to circumference in a circle) at 3.1416—a figure not equaled in accuracy until the days of Purbach (1423-61) in Europe. Bhaskara crudely anticipated the differential calculus, Aryabhata drew up a table of sines, and the Surya Siddhanta provided a system of trigonometry more advanced than anything known to the Greeks."

"It was India, not Greece, that taught Islam in the impressionable years of its youth, formed its philosophy and esoteric religious ideals, and inspired its most characteristic expression in literature, art and architecture."

"Said the great and magnanimous Laplace: 'It is India that gave us the ingenious method of expressing all numbers by ten symbols, each receiving a value of position as well as an absolute value; a profound and important idea which appears so simple to us now that we ignore its true merit. But its very simplicity, the great ease which it has lent to all computations, puts our arithmetic in the first rank of useful inventions; and we shall appreciate the grandeur of this achievement the more when we remember that it escaped the genius of Archimedes and Apollonius, two of the greatest men produced by antiquity.'"

"The Encyclopaedia of Diderot likewise suggested, in the article on India, that the"sciences may be more ancient in India than in Egypt"."

"Many of the advances in the sciences that we consider today to have been made in Europe were in fact made in India centuries ago."

"The sciences may be more ancient in India than in Egypt."

"The motion of the stars calculated by the Hindus some 4500 years before vary not even a single minute from the modern tables of Cassini and Meyer."

"Hindu sciences have retired far away from those parts of the country conquered by us, and have fled to places which our hand cannot yet reach, to Kashmir, Benaras and other places."

"INDIA'S work in science is both very old and very young: young as an independent and secular pursuit, old as a subsidiary interest of her priests."

"The Hindu systems of astronomy are by far the oldest, and that from which the Egyptians, Greeks, Romans, and even the Jews derived Hindus their knowledge."

"To make these complex calculations the Hindus developed a system of mathematics superior, in everything except geometry, to that of the Greeks. Among the most vital parts of our Oriental heritage are the “Arabic” numerals and the decimal system, both of which came to us, through the Arabs, from India. The miscalled “Arabic” numerals are found on the Rock Edicts of Ashoka (256 B.C.), a thousand years before their occurrence in Arabic literature."

"The decimal system was known to Aryabhata and Brahmagupta long before its appearance in the writings of the Arabs and the Syrians; it was adopted by China from Buddhist missionaries; and Muhammad Ibn Musa al-Khwarazmi, the greatest mathematician of his age (d. ca. 850 A.D.), seems to have introduced it into Baghdad. The oldest known use of the zero in Asia or EuropeI is in an Arabic document dated 873 A.D., three years sooner than its first known appearance in India; but by general consent the Arabs borrowed this too from India, and the most modest and most valuable of all numerals is one of the subtle gifts of India to mankind."

"Algebra was developed in apparent independence by both the Hindus and the Greeks; but our adoption of its Arabic name (al-jabr, adjustment) indicates that it came to western Europe from the Arabs—i.e., from India—rather than from Greece. The great Hindu leaders in this field, as in astronomy, were Aryabhata, Brahmagupta and Bhaskara. The last (b. 1114 A.D.), appears to have invented the radical sign, and many algebraic symbols. These men created the conception of a negative quantity, without which algebra would have been impossible; they formulated rules for finding permutations and combinations; they found the square root of 2, and solved, in the eighth century A.D., indeterminate equations of the second degree that were unknown to Europe until the days of Euler a thousand years later.14 They expressed their science in poetic form, and gave to mathematical problems a grace characteristic of India’s Golden Age."

"Classical mechanics"

"When the theory of relativity supplanted classical science, it was recognised that the classical equations of mechanics were only approximate, and it became necessary to reformulate the principle of action so as to render it compatible... This work was carried out by the pure mathematicians—by Klein and Hilbert in particular. It was then found that a principle of action differing but slightly from the classical one could be obtained."

"In classical science, it was strange to find that action... should yet present the artificial aspect of an energy in space multiplied by a duration. As soon, however, as we realise that the fundamental continuum of the universe is one of space-time and not one of separate space and time, the reason for the importance of the seemingly artificial combination of space with time in the expression for the action receives a very simple explanation. Henceforth, action is no longer energy in a volume of space multiplied by a duration; it is simply energy in a volume of the world, that is to say, in a volume of four-dimensional space-time. Designating a volume of space-time by d\omega, we haved\omega = dxdydzdt,so that our principle of action, \partial A = 0, becomes\partial \int\,L\,d\omega = 0.Now there is a perfect symmetry between the rôles of space and time."

"From the expression for the atom of energy or quantum hv, where h is a constant and v is the frequency of the radiation, it is obvious that there exist as many different types of quanta of energy as there exist different frequencies of radiation. There is no unique type of quantum of energy in nature. That which is universal is not the quantum of energy hv, but the constant h. It can be shown that Planck's constant h is not a mere number; it represents some definite abstract mathematical entity, and that entity is action. We must assume, therefore, that there exist atoms of action in nature, just as there exist atoms of matter. ...we must possess a fairly thorough understanding of what is meant by action, as also of the part this important entity plays in science. ...the atomicity of action ...suggests that change is always discontinuous ...a series of jerks or jumps."

"The principle... imposes the condition that the natural evolution of any system must be such as to render the action a maximum or a minimum. Could we but express this condition in terms of the usual physical magnitudes, we should be enabled to map out in advance the series of intermediary states through which the phenomenon would pass. From this knowledge we should derive the expression of the laws which governed the evolution of the phenomenon. Here... a twofold problem presents itself. First, we must succeed in finding the correct mathematical expression for the action; and, secondly, we must be in a position to solve the purely mathematical problem of determining under what conditions the action will be a maximum or a minimum. Now all problems of maxima and minima are solve by means of the calculus of variations, a form of calculus we owe chiefly to Lagrange. According to the methods of this calculus, we establish under what conditions a magnitude is a maximum or minimum by discovering under what conditions it will be stationary. ... When a stone is thrown into the air, it ascends with decreasing speed, then seems to hesitate for a brief period of time as it hovers near the point of maximum height before it starts to fall back again towards the earth. During this brief period of hesitation at the apex of its trajectory, the stone is said to remain "stationary." We can recognize a stationary state by observing that when it is reached no perceptible changes take place over a short period of time. In this way, we understand the connection which exists between the stationary condition and the presence of a maximum or a minimum. In mathematics small variations are represented by the letter δ; hence the stationary condition of the action, or again, the principle of action, is expressed by\partial A = 0,~ ~i.e.,~\partial \iiiint\,L\,dx\,dy\,dz\,dt = 0....Lamor applied this method to the phenomena of electricity and magnetism and showed how Maxwell's laws of electrodynamics could be deduced from a suitable mathematical expression L defining the electromagnetic function of action."

"In order to understand the significance of Action, let us consider any mechanical system passing from an initial configuration P to a final configuration Q. Classical science defined the action A of this system as the difference between its total kinetic energy... and its total potential energy... taken at every instant and then summated over the entire period of time during which the system passed from the initial state P to the final state Q. Now the total kinetic and potential energies of the system at any instant are given by\iiint\,T\,dx\,dy\,dz~ ~and~ \iiint\,V\,dx\,dy\,dz,where T and V represent the densities of the kinetic and potential energies of every point throughout the space occupied by the system. Accordingly, the expression of the action will be given byA = \iiiint\,(T-V)\,dx\,dy\,dz\,dt~ ~or~ \iiiint\,L\,dx\,dy\,dz\,dt....we have merely replaced (T - V) by a single letter L... referred to as the function of action (also called Lagrangian function). Roughly speaking, action was thus in the nature of the product of a duration by an energy contained in a volume of space. On no account may this action be confused with the action dealt with in Newton's law of action and reaction, also expressible as the principle of conservation of momentum. Still less may it be confused with the term "action" which appears in philosophical writings. ...the laws of mechanics can be expressed in a highly condensed form when the concept of action is introduced. Various forms may be given to the principle of Action; here we consider only the form... called Hamilton's Principle of Stationary Action. If we restrict our attention to the very simplest case, we may state Hamilton's principle as follows: If we consider all the varied paths along which a conservative system may be guided, so that it will pass in a given time from a definite initial configuration P to a definite configuration Q, we shall find that the course the system actually follows, of its own accord, is always such that along it the action is a minimum (or a maximum). ...the principle of action issues ...from the laws of classical mechanics ...A priori, we have no means of deciding whether the laws governing physical phenomena of a non-mechanical nature—those of electromagnetics, for example—would issue from the same principle of action."