’Tis a short sight to limit our faith in laws to those of gravity, of chemistry, of botany, and so forth. Those laws do not stop where our eyes lose them, but push the same geometry and chemistry up into the invisible plane of social and rational life, so that, look where we will, in a boy's game, or in the strifes of races, a perfect reaction, a perpetual judgment keeps watch and ward.

“Every moment dies a man,/ Every moment one is born”:
I need hardly point out to you that this calculation would tend to keep the sum total of the world's population in a state of perpetual equipoise whereas it is a well-known fact that the said sum total is constantly on the increase. I would therefore take the liberty of suggesting that in the next edition of your excellent poem the erroneous calculation to which I refer should be corrected as follows:
'Every moment dies a man / And one and a sixteenth is born.” I may add that the exact figures are 1.167, but something must, of course, be conceded to the laws of metre.

[Ignorance] of the principle of conservation of energy … does not prevent inventors without background from continually putting forward perpetual motion machines… Also, such persons undoubtedly have their exact counterparts in the fields of art, finance, education, and all other departments of human activity… persons who are unwilling to take the time and to make the effort required to find what the known facts are before they become the champions of unsupported opinions—people who take sides first and look up facts afterward when the tendency to distort the facts to conform to the opinions has become well-nigh irresistible.

Dilbert: I’m obsessed with inventing a perpetual motion machine. Most scientists think it's impossible, but I have something they don’t.
Dogbert: A lot of spare time?
Dilbert: Exactly.

According to their [Newton and his followers] doctrine, God Almighty wants to wind up his watch from time to time: otherwise it would cease to move. He had not, it seems, sufficient foresight to make it a perpetual motion. Nay, the machine of God's making, so imperfect, according to these gentlemen; that he is obliged to clean it now and then by an extraordinary concourse, and even to mend it, as clockmaker mends his work.

After seeking in vain for the construction of a perpetual motion machine, the relations were investigated which must subsist between the forces of nature if such a machine is to be impossible; and this inverted question led to the discovery of the law of the conservation of energy, which, again, explained the impossibility of perpetual motion in the sense originally intended.

Alike in the external and the internal worlds, the man of science sees himself in the midst of perpetual changes of which he can discover neither the beginning nor the end.

All things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence ... there is an enormous amount of information about the world.
His suggestion that the most valuable information on scientific knowledge in a single sentence using the fewest words is to state the atomic hypothesis.

An acquaintance of mine, a notary by profession, who, by perpetual writing, began first to complain of an excessive wariness of his whole right arm which could be removed by no medicines, and which was at last succeeded by a perfect palsy of the whole arm. … He learned to write with his left hand, which was soon thereafter seized with the same disorder.

An Individual, whatever species it might be, is nothing in the Universe. A hundred, a thousand individuals are still nothing. The species are the only creatures of Nature, perpetual creatures, as old and as permanent as it. In order to judge it better, we no longer consider the species as a collection or as a series of similar individuals, but as a whole independent of number, independent of time, a whole always living, always the same, a whole which has been counted as one in the works of creation, and which, as a consequence, makes only a unity in Nature.

Being perpetually charmed by his familiar siren, that is, by his geometry, he [Archimedes] neglected to eat and drink and took no care of his person; that he was often carried by force to the baths, and when there he would trace geometrical figures in the ashes of the fire, and with his finger draws lines upon his body when it was anointed with oil, being in a state of great ecstasy and divinely possessed by his science.

But we have reason to think that the annihilation of work is no less a physical impossibility than its creation, that is, than perpetual motion.

Considered from the standpoint of chemistry, living bodies appear to us as laboratories of chemical processes, for they undergo perpetual changes in their material substrate. They draw materials from the outside world and combine them with the mass of their liquid and solid parts.

Constant, or free, life is the third form of life; it belongs to the most highly organized animals. In it, life is not suspended in any circumstance, it unrolls along a constant course, apparently indifferent to the variations in the cosmic environment, or to the changes in the material conditions that surround the animal. Organs, apparatus, and tissues function in an apparently uniform manner, without their activity undergoing those considerable variations exhibited by animals with an oscillating life. This because in reality the internal environment that envelops the organs, the tissues, and the elements of the tissues does not change; the variations in the atmosphere stop there, so that it is true to say that physical conditions of the environment are constant in the higher animals; it is enveloped in an invariable medium, which acts as an atmosphere of its own in the constantly changing cosmic environment. It is an organism that has placed itself in a hot-house. Thus the perpetual changes in the cosmic environment do not touch it; it is not chained to them, it is free and independent.

Ever since I was a boy, I’ve been fascinated by crazy science and such things as perpetual motion machines and logical paradoxes. I’ve always enjoyed keeping up with those ideas. I suppose I didn’t get into it seriously until I wrote my first book, Fads and Fallacies in the Name of Science. I was influenced by the Dianetics movement, now called Scientology, which was then promoted by John Campbell in Astounding Science Fiction. I was astonished at how rapidly the thing had become a cult.

Every living language, like the perspiring bodies of living creatures, is in perpetual motion and alteration; some words go off, and become obsolete; others are taken in, and by degrees grow into common use; or the same word is inverted to a new sense and notion, which in tract of time makes as observable a change in the air and features of a language as age makes in the lines and mien of a face.

For FRICTION is inevitable because the Universe is FULL of God's works.
For the PERPETUAL MOTION is in all works of Almighty GOD.
For it is not so in the engines of man, which are made of dead materials, neither indeed can be.
For the Moment of bodies, as it is used, is a false term—bless God ye Speakers on the Fifth of November.
For Time and Weight are by their several estimates.
For I bless GOD in the discovery of the LONGITUDE direct by the means of GLADWICK.
For the motion of the PENDULUM is the longest in that it parries resistance.
For the WEDDING GARMENTS of all men are prepared in the SUN against the day of acceptation.
For the wedding Garments of all women are prepared in the MOON against the day of their purification.
For CHASTITY is the key of knowledge as in Esdras, Sir Isaac Newton & now, God be praised, in me.
For Newton nevertheless is more of error than of the truth, but I am of the WORD of GOD.

For me, physics cultivates a perpetual state of wonder about the limits of thoughts, the workings of the universe, and our place in the vast space-time landscape that we call home.

I am above the forest region, amongst grand rocks & such a torrent as you see in Salvator Rosa's paintings vegetation all a scrub of rhodods. with Pines below me as thick & bad to get through as our Fuegian Fagi on the hill tops, & except the towering peaks of P. S. [perpetual snow] that, here shoot up on all hands there is little difference in the mt scenery—here however the blaze of Rhod. flowers and various colored jungle proclaims a differently constituted region in a naturalists eye & twenty species here, to one there, always are asking me the vexed question, where do we come from?

I am sorry the infernal Divinities, who visit mankind with diseases, and are therefore at perpetual war with Doctors, should have prevented my seeing all you great Men at Soho to-day-Lord! what inventions, what wit, what rhetoric, metaphysical, mechanical and pyrotecnical, will be on the wing, bandy'd like a shuttlecock from one to another of your troop of philosophers! while poor I, I by myself I, imprizon'd in a post chaise, am joggled, and jostled, and bump'd, and bruised along the King's high road, to make war upon a pox or a fever!

I have said that mathematics is the oldest of the sciences; a glance at its more recent history will show that it has the energy of perpetual youth. The output of contributions to the advance of the science during the last century and more has been so enormous that it is difficult to say whether pride in the greatness of achievement in this subject, or despair at his inability to cope with the multiplicity of its detailed developments, should be the dominant feeling of the mathematician. Few people outside of the small circle of mathematical specialists have any idea of the vast growth of mathematical literature. The Royal Society Catalogue contains a list of nearly thirty- nine thousand papers on subjects of Pure Mathematics alone, which have appeared in seven hundred serials during the nineteenth century. This represents only a portion of the total output, the very large number of treatises, dissertations, and monographs published during the century being omitted.

If a man would be alone, let him look at the stars. … One might think the atmosphere was made transparent with this design, to give man, in the heavenly bodies, the perpetual presence of the sublime.

If in our withered leaves you see
Hint of your own mortality:—
Think how, when they have turned to earth,
New loveliness from their rich worth
Shall spring to greet the light; then see
Death as the keeper of eternity,
And dying Life’s perpetual re-birth !

If, in the course of a thousand or two thousand years, science arrives at the necessity of renewing its points of view, that will not mean that science is a liar. Science cannot lie, for it’s always striving, according to the momentary state of knowledge, to deduce what is true. When it makes a mistake, it does so in good faith. It’s Christianity that’s the liar. It’s in perpetual conflict with itself.

In essence, science is a perpetual search for an intelligent and integrated comprehension of the world we live in.

It hath been an old remark, that Geometry is an excellent Logic. And it must be owned that when the definitions are clear; when the postulata cannot be refused, nor the axioms denied; when from the distinct contemplation and comparison of figures, their properties are derived, by a perpetual well-connected chain of consequences, the objects being still kept in view, and the attention ever fixed upon them; there is acquired a habit of reasoning, close and exact and methodical; which habit strengthens and sharpens the mind, and being transferred to other subjects is of general use in the inquiry after truth.

It is difficult to conceive a grander mass of vegetation:—the straight shafts of the timber-trees shooting aloft, some naked and clean, with grey, pale, or brown bark; others literally clothed for yards with a continuous garment of epiphytes, one mass of blossoms, especially the white Orchids Caelogynes, which bloom in a profuse manner, whitening their trunks like snow. More bulky trunks were masses of interlacing climbers, Araliaceae, Leguminosae, Vines, and Menispermeae, Hydrangea, and Peppers, enclosing a hollow, once filled by the now strangled supporting tree, which has long ago decayed away. From the sides and summit of these, supple branches hung forth, either leafy or naked; the latter resembling cables flung from one tree to another, swinging in the breeze, their rocking motion increased by the weight of great bunches of ferns or Orchids, which were perched aloft in the loops. Perpetual moisture nourishes this dripping forest: and pendulous mosses and lichens are met with in profusion.

Man is merely a frequent effect, a monstrosity is a rare one, but both are equally natural, equally inevitable, equally part of the universal and general order. And what is strange about that? All creatures are involved in the life of all others, consequently every species... all nature is in a perpetual state of flux. Every animal is more or less a human being, every mineral more or less a plant, every plant more or less an animal... There is nothing clearly defined in nature.

Many billions of years will elapse before the smallest, youngest stars complete their nuclear burning and into white dwarfs. But with slow, agonizing finality perpetual night will surely fall.

Mathematics is one of the oldest of the sciences; it is also one of the most active, for its strength is the vigour of perpetual youth.

Nothing is constant but change! All existence is a perpetual flux of “being and becoming!” That is the broad lesson of the evolution of the world.

Physics inquires whether the world is eternal, or perpetual, or had a beginning and will have an end in time, or whether none of these alternatives is accurate.

Progress, far from consisting in change, depends on retentiveness. When change is absolute there remains no being to improve and no direction is set for possible improvement: and when experience is not retained, as among savages, infancy is perpetual. Those who cannot remember the past are condemned to repeat it.

Real life is, to most men, a long second-best, a perpetual compromise between the ideal and the possible; but the world of pure reason ;knows no compromise, no practical limitations, no barrier to the creative activity.

Science … is perpetually advancing. It is like a torch in the sombre forest of mystery. Man enlarges every day the circle of light which spreads round him, but at the same time, and in virtue of his very advance, he finds himself confronting, at an increasing number of points, the darkness of the Unknown.

Science has its being in a perpetual mental restlessness.

Science is not about control. It is about cultivating a perpetual sense of wonder in the face of something that forever grows one step richer and subtler than our latest theory about it. It is about reverence, not mastery.

Seeing therefore the variety of Motion which we find in the World is always decreasing, there is a necessity of conserving and recruiting it by active Principles, such as are the cause of Gravity, by which Planets and Comets keep their Motions in their Orbs, and Bodies acquire great Motion in falling; and the cause of Fermentation, by which the Heart and Blood of Animals are kept in perpetual Motion and Heat; the inward Parts of the Earth are constantly warm'd, and in some places grow very hot; Bodies burn and shine, Mountains take fire, the Caverns of the Earth are blown up, and the Sun continues violently hot and lucid, and warms all things by his Light. For we meet with very little Motion in the World, besides what is owing to these active Principles.

Since a given system can never of its own accord go over into another equally probable state but into a more probable one, it is likewise impossible to construct a system of bodies that after traversing various states returns periodically to its original state, that is a perpetual motion machine.

Sir Edward has calculated that quick-growing Indian eucalyptus trees have a yield of nine and one-quarter tons of wood an acre a year. As the wood contains 0.8 per cent of the solar energy reaching the ground in the tropics in the form of heat, Sir Edward has suggested that in theory eucalyptus forests could provide a perpetual source of fuel. He has said that by rotational tree planting and felling, a forest of twenty kilometers square would enable a wood consuming power station to provide 10,000 kilowatts of power.

The biologist can push it back to the original protist, and the chemist can push it back to the crystal, but none of them touch the real question of why or how the thing began at all. The astronomer goes back untold million of years and ends in gas and emptiness, and then the mathematician sweeps the whole cosmos into unreality and leaves one with mind as the only thing of which we have any immediate apprehension. Cogito ergo sum, ergo omnia esse videntur. All this bother, and we are no further than Descartes. Have you noticed that the astronomers and mathematicians are much the most cheerful people of the lot? I suppose that perpetually contemplating things on so vast a scale makes them feel either that it doesn’t matter a hoot anyway, or that anything so large and elaborate must have some sense in it somewhere.

The difficulty really is psychological and exists in the perpetual torment that results from your saying to yourself, “But how can it be like that?” which is a reflection of uncontrolled but utterly vain desire to see it in terms of something familiar. … If you will simply admit that maybe [Nature] does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself, if you can possible avoid it, "But how can it be like that?" because you will get 'down the drain', into a blind alley from which nobody has escaped. Nobody knows how it can be like that.
[About wave-particle duality.]

The large collection of problems which our modern Cambridge books supply will be found to be almost an exclusive peculiarity of these books; such collections scarcely exist in foreign treatises on mathematics, nor even in English treatises of an earlier date. This fact shows, I think, that a knowledge of mathematics may be gained without the perpetual working of examples. … Do not trouble yourselves with the examples, make it your main business, I might almost say your exclusive business, to understand the text of your author.

The most striking characteristic of the written language of algebra and of the higher forms of the calculus is the sharpness of definition, by which we are enabled to reason upon the symbols by the mere laws of verbal logic, discharging our minds entirely of the meaning of the symbols, until we have reached a stage of the process where we desire to interpret our results. The ability to attend to the symbols, and to perform the verbal, visible changes in the position of them permitted by the logical rules of the science, without allowing the mind to be perplexed with the meaning of the symbols until the result is reached which you wish to interpret, is a fundamental part of what is called analytical power. Many students find themselves perplexed by a perpetual attempt to interpret not only the result, but each step of the process. They thus lose much of the benefit of the labor-saving machinery of the calculus and are, indeed, frequently incapacitated for using it.

The prodigious waste of human life occasioned by this perpetual struggle for room and food, was more than supplied by the mighty power of population, acting, in some degree, unshackled, from the constant habit of emigration.

The recipe for perpetual ignorance is: be satisfied with your opinions and content with your knowledge.

The subsequent course of nature, teaches, that God, indeed, gave motion to matter; but that, in the beginning, he so guided the various motion of the parts of it, as to contrive them into the world he design'd they should compose; and establish'd those rules of motion, and that order amongst things corporeal, which we call the laws of nature. Thus, the universe being once fram'd by God, and the laws of motion settled, and all upheld by his perpetual concourse, and general providence; the same philosophy teaches, that the phenomena of the world, are physically produced by the mechanical properties of the parts of matter; and, that they operate upon one another according to mechanical laws. 'Tis of this kind of corpuscular philosophy, that I speak.

The wintry clouds drop spangles on the mountains. If the thing occurred once in a century historians would chronicle and poets would sing of the event; but Nature, prodigal of beauty, rains down her hexagonal ice-stars year by year, forming layers yards in thickness. The summer sun thaws and partially consolidates the mass. Each winter's fall is covered by that of the ensuing one, and thus the snow layer of each year has to sustain an annually augmented weight. It is more and more compacted by the pressure, and ends by being converted into the ice of a true glacier, which stretches its frozen tongue far down beyond the limits of perpetual snow. The glaciers move, and through valleys they move like rivers.

The work of the true man of Science is a perpetual striving after a better and closer knowledge of the planet on which his lot is cast, and of the universe in the vastness of which that planet is lost. The only way of doing this effectually, is to proceed as gradually, and therefore as surely as possible, along the dim untrodden ground lying beyond the known. Such is scientific work.

There are those who say that the human kidney was created to keep the blood pure, or more precisely, to keep our internal environment in an ideal balanced state. This I must deny. I grant that the human kidney is a marvelous organ, but I cannot grant that it was purposefully designed to excrete urine or to regulate the composition of the blood or to subserve the physiological welfare of Homo sapiens in any sense. Rather I contend that the human kidney manufactures the kind of urine that it does, and it maintains the blood in the composition which that fluid has, because this kidney has a certain functional architecture; and it owes that architecture not to design or foresight or to any plan, but to the fact that the earth is an unstable sphere with a fragile crust, to the geologic revolutions that for six hundred million years have raised and lowered continents and seas, to the predacious enemies, and heat and cold, and storms and droughts; to the unending succession of vicissitudes that have driven the mutant vertebrates from sea into fresh water, into desiccated swamps, out upon the dry land, from one habitation to another, perpetually in search of the free and independent life, perpetually failing, for one reason or another, to find it.

This conviction of the solvability of every mathematical problem is a powerful incentive to the worker. We hear within us the perpetual call: There is the problem. Seek its solution. You can find it by pure reason, for in mathematics there is no ignorabimus!

This perpetual motion machine she [Lisa] made today is a joke, it just keeps going faster and faster…. Lisa … In this house, we OBEY the laws of thermodynamics!

Time is a perpetual perishing.

To the mind which looks not to general results in the economy of Nature, the earth may seem to present a scene of perpetual warfare, and incessant carnage: but the more enlarged view, while it regards individuals in their conjoint relations to the general benefit of their own species, and that of other species with which they are associated in the great family of Nature, resolves each apparent case of individual evil, into an example of subserviency to universal good.

Truth is compared in Scripture to a streaming fountain; if her waters flow not in perpetual progression, they sicken into a muddy pool of conformity and tradition.

Well, evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world’s data. Theories are structures of ideas that explain and interpret facts. Facts do not go away while scientists debate rival theories for explaining them. Einstein’s theory of gravitation replaced Newton’s, but apples did not suspend themselves in mid-air pending the outcome. And human beings evolved from apelike ancestors whether they did so by Darwin’s proposed mechanism or by some other, yet to be discovered … Evolutionists make no claim for perpetual truth, though creationists often do (and then attack us for a style of argument that they themselves favor).

What can I say of the perpetual motion machine that is my husband? What makes Francis run? It is a mysterious and propelling force which, injected into all mankind, would solve all the problems that plague this day and age.
Describing her husband, opthalmologist Francis Heed Adler.

What is there about fire that's so lovely? ... It's perpetual motion; the thing man wanted to invent but never did. Or almost perpetual motion. ... What is fire? It's a mystery. Scientists give us gobbledegook about friction and molecules. But they don't really know.
[Fahrenheit 451 refers to the temperature at which book paper burns. In the short novel of this title 'firemen' burn books forbidden by the totalitaran regime.]

What of the future of this adventure? What will happen ultimately? We are going along guessing the laws; how many laws are we going to have to guess? I do not know. Some of my colleagues say that this fundamental aspect of our science will go on; but I think there will certainly not be perpetual novelty, say for a thousand years. This thing cannot keep on going so that we are always going to discover more and more new laws … It is like the discovery of America—you only discover it once. The age in which we live is the age in which we are discovering the fundamental laws of nature, and that day will never come again. Of course in the future there will be other interests … but there will not be the same things that we are doing now … There will be a degeneration of ideas, just like the degeneration that great explorers feel is occurring when tourists begin moving in on a territory.