Bernard Le Bovier de Fontenelle’s Conversations on the Plurality of Worlds is a work of popular science written as a series of dialogues. Over six evenings in a country house, a narrator explains the new astronomy to a noblewoman, the Countess, moving from the Copernican system to the claim that the Moon, the planets, and the fixed stars are all inhabited worlds. The English translation by William Gardiner appeared in London in the early eighteenth century, and the book wears its learning lightly, aiming to divert as much as to instruct.
Fontenelle’s preface sets the terms of the enterprise. He wants to discuss philosophy without the dry apparatus of the schools, raising it to a pitch “neither too dry for gentlemen nor too mean for scholars.” Those already versed in natural philosophy should be diverted by seeing in a gay dress what they have met in graver form; newcomers should be both diverted and instructed. The Countess is his device for making the subject acceptable to gentlewomen: a woman without supernatural parts or tincture of learning who nonetheless grasps what vortices and other worlds are. He asks the fair sex to read his system with the same application they give a romance, and he insists his visions have some real foundation, true and false mingled but easily distinguished. To scrupulous readers who fear that peopling other worlds endangers religion, he answers that no one of Adam’s posterity ever traveled to the Moon, so its inhabitants are not the Sons of Adam—and besides, he never said there are men there.
Cicero’s Example and the Countess’s Education
The 1715 London edition, translated by William Gardiner, opens with a preface in which Fontenelle explains his design by way of Cicero. When Cicero was urged to write philosophy in Latin, he answered that admirers of philosophy would read the Greek authors anyway, while everyone else would ignore the subject entirely; Latin books, he said, might tempt ordinary people to become philosophers and let existing philosophers see the subject handled in their own tongue. Fontenelle admires the reply but admits he lacks Cicero’s genius and reputation to carry it off. His own aim is to discuss philosophy without the full apparatus of the schools, raising it to a pitch neither too dry for gentlemen nor too mean for scholars. He does not pretend to instruct those already versed in natural philosophy but to divert them by presenting in a gay dress what they have seen in graver form; newcomers to the subject may be both diverted and instructed. He chose the part of philosophy most likely to excite curiosity—how this world is made, and whether other worlds exist and are inhabited—leaving each reader to pursue such questions as far as he pleases.
To make the book acceptable, he introduces a Lady to be instructed in things she never heard of, encouraging gentlewomen by the example of one of their own sex who, without supernatural parts or tincture of learning, understands what is said and rightly apprehends what Vortexes and other Worlds are. Why, he asks, might there not be a woman like this imaginary Countess? Penetrating obscure things requires deep meditation, but here one need only read and imprint the idea on the fancy; he asks the fair sex to peruse his system with the same application they give a romance or novel, since its ideas are less familiar to most ladies than those of romances but not more obscure. He has not composed an airy system without foundation but used true philosophical arguments, and the physical ideas, while convincing reason, present to the imagination a prospect made to please it. Digressions he uses sparingly, mostly at the beginning of the book and taken from the subject itself. Concerning the inhabitants of the many worlds he says nothing fabulous: his visions have some real foundation, true and false mingled but easily distinguished. Finally he addresses scrupulous persons who imagine that placing inhabitants anywhere but on the Earth endangers religion. When it is said the Moon is inhabited, some fancy there are men like us there, and churchmen think him an atheist; but no one of Adam’s posterity ever traveled to the Moon nor were colonies sent thither, so the men there are not the Sons of Adam—a difficulty theology would be puzzled by. He never said there are Men there; if asked what the inhabitants are, he can say he never saw them. And he says there are no Men in the Moon not merely to dodge the objection, for it appears impossible there should be any, according to his idea of the infinite diversity and variety observed in the Works of Nature. This edition, he notes, adds a New Conversation gathering reasonings omitted from the others, together with several late discoveries in the firmament never yet made public.
Astronomy’s Chaldaean Birth
The table of contents lays out six evenings: that the Earth is a planet turning on itself and round the Sun; that the Moon is an inhabited world; particulars of the world in the Moon and proofs that the other planets are likewise inhabited; particulars of Venus, Mercury, Mars, Jupiter and Saturn; that the fixed stars are so many suns, each giving light to a world; and new observations confirming the preceding discourses, with late discoveries in the heavens.
The First Evening opens with the narrator addressing a letter to a gentleman, then turning to the Countess. Astronomy, he tells her, was born in Chaldaea, as geometry sprang from Egypt, where the Nile’s flooding confused field boundaries and forced the invention of more exact measures. Hence Astronomy is called the Daughter of Idleness, Geometry the Daughter of Interest, and Poetry the Daughter of Love. The Countess is delighted with this genealogy of the sciences: her soul, she says, is neither mercenary enough for Geometry nor tender enough for Poetry, and she has as much spare time as Astronomy requires, especially now in the country leading a pastoral life. He warns her not to deceive herself—talking of stars and planets is a true shepherd’s life, but the shepherds of Arcadia passed their time otherwise, and that craft is too dangerous for her to learn; he prefers the honest Chaldaeans and their rules.
The Crystal Heavens and the King of Aragon
The next question after ranking the heavens is disposing the parts of the universe—what the learned call making a system. Before expounding the first, the narrator observes that we are all like the madman at Athens who fancied every ship entering the Piraeum belonged to him: we believe all things in nature designed for our use. Ask why there is such a prodigious company of fixed stars when a far lesser number would serve, and a philosopher answers coldly that they were made to please our sight. On this principle the ancients imagined the Earth at rest in the center of the universe while all celestial bodies, made for it, turned round to give it light. They placed the Moon above the Earth, Mercury above the Moon, then Venus, the Sun, Mars, Jupiter, Saturn, and above all these the heaven of fixed stars. The Earth stood in the middle of the planetary circles; the greater the circle, the farther from the Earth, so the farthest planets took most time to finish their course—which is in effect true.
The Countess interrupts: why does he dislike a system so clear and intelligible? Because, he says, if given as it came from Ptolemy or his successors it would fright rather than divert her. The planets’ motions are not so regular but that they sometimes go faster, sometimes slower, sometimes nearer the Earth and sometimes farther; so the ancients invented many orbs or circles involved one within another to salve all objections. This confusion was so great that a certain King of Aragon, a great mathematician but not much troubled with religion, said that had God consulted him when He made the worlds, He would have been told how to frame them better—a very atheistical saying, the narrator grants, and he supposes the instructions would have been the suppressing of those circles and the removal of two or three superfluous heavens above the fixed stars. To explain celestial motion these philosophers placed above the uppermost visible heaven another of crystal to influence the inferior heavens; whenever they heard of another motion, they clapped up a crystal heaven, which cost them nothing. Why crystal? Nothing else would serve, for light was to come through them and yet they were to be solid—Aristotle would have it so, and once he had said it nobody would question it. But comets appeared much higher than expected and, passing, broke the crystal heavens and confounded the universe; the philosophers melted down their broken glass and, to Aristotle’s confusion, made the heavens fluid. By the observations of latter ages it is now out of doubt that Venus and Mercury turn round the Sun and not round the Earth, and the ancient system is everywhere exploded, all authorities not worth a rush.
Copernicus Strikes the Earth from Its Place
What the narrator will lay down salves all and is so clear that the King of Aragon may spare his advice. The Countess remarks that his philosophy is a kind of outcry where he who offers to do the work cheapest carries it from all the rest. He agrees: Nature is a great housewife, always using what costs least, yet her frugality is accompanied with extraordinary magnificence—magnificent in the design, frugal in the execution. We turn things topsy-turvy, placing our thrift in the design and spending ten times more in workmanship than needed. She bids him imitate Nature and give her as little trouble as possible.
He then introduces a German called Copernicus, who, confounding everything, tearing in pieces the beloved circles of antiquity and shattering their crystal heavens like glass windows, seized with the noble rage of astronomy, snatches the Earth from the center of the universe, sends her packing, and places the Sun in the center, to which it more justly belonged.
Natural Barricades and the Moon’s Spectacles
The narrator warns the Countess that she would be sick if drawn to the top of our air, since it cannot be breathed in all its extent—as anyone knows from very high mountains. He marvels that those who believe in corporeal Fairies inhabiting the purest air never explain their short, rare visits by saying few Fairies can dive and those that can cannot stay long in thick air, as diving fowls do in water. These are natural barricades defending passage out of our world and entry into the Moon’s; since we can only guess at that world, we should fancy what we can. The Moon’s firmament, Sun, and stars may appear of another color, seen through natural spectacles that alter objects—these spectacles being our air, mixed with vapors and exhalations and not extending very high. Some modern philosophers hold that air is of itself blue, like sea water, the color appearing only at great depth; that the firmament where fixed stars are fastened has no light of its own and must appear black, but we see it through blue air and so it appears blue. If so, the Sun’s and stars’ beams cannot pass through air without being tinged with its color and losing some of their own. Even colorless air: through a great mist a distant flambeau’s light appears reddish, not its true color. Our air is nothing but a great mist changing the true color of sky, Sun, and stars; only the celestial matter brings light and colors in their purity. Since the Moon’s air is of another nature, stained another color, or another kind of mist causing other alterations, the Moon-dwellers’ spectacles are changed.
The Count says he prefers his abode to the Moon’s, disbelieving celestial colors are so well suited as here—green stars on a red sky cannot be as agreeable as gold stars on an azure firmament. The speaker replies one would think he was choosing a petticoat or suit of knots; Nature does not want Fancy—leave her to choose the Moon’s colors, which shall be well sorted, varying the prospect at every point of view agreeably. The Countess says she knows Nature’s skill: she does not pay to change objects but only the spectacles, getting credit for variety without expense—with blue air she gives a blue firmament, perhaps with red air a red firmament to Moon inhabitants, yet it is the same firmament. She opines Nature has placed spectacles in our imagination through which we see all things, changing objects for every particular man: Alexander looked on Earth as fit for a great empire; to Cæsar it seemed a proper residence for Astrea; to a philosopher it appeared a great planet covered with fools. Sights vary no more between Earth and Moon than between one man’s fancy and another’s.
The speaker says this change in imaginations is surprising, for objects remain the same though they appear different. In the Moon we may see objects not seen here, or not see all we see here; perhaps there they know nothing of dawn and twilight before sunrise and after sunset. The air encompassing and elevated above us receives rays so they cannot strike the Earth, and being gross stops some and sends them to us though never naturally designed for us; so day-break and twilight are a favor Nature bestows, a light regularly we should not have, given over and above our due. In the Moon, where apparently the air is more pure and less proper to send down beams received before sunrise and after sunset, they lack that light of grace which growing greater by degrees prepares them for the Sun’s arrival and, weakening, for its departure; instead they are in profound darkness where a curtain is drawn all on a sudden, their eyes immediately dazzled with the whole light of the Sun, and on a sudden surprised with utter darkness—night and day have no medium, falling in a moment from one extreme to the other. The rainbow likewise is unknown there; if dawn is an effect of the grossness of air and vapors, the rainbow is formed in clouds whence rain falls, so the world’s most beautiful things are produced by things with no beauty. Since there are no vapors thick enough nor rain clouds about the Moon, farewell dawn, adieu rainbow—what must lovers do for similes in that country when such an inexhaustible magazine of comparisons is taken from them?
The Countess says she shall never take the loss of their comparisons to heart, thinking them well enough recompensed for the loss of our dawn and rainbow; by the same reason they have neither thunder nor lightning, both formed in clouds. How glorious their days, the Sun continually shining; how pleasant their nights, not the least star hid. They never hear of storms or tempests, plain effects of the wrath of Heaven. The speaker asks if she thinks they need our pity, saying she describes the Moon like an enchanted residence; but is it so pleasant to have a scorching Sun always overhead, where days are fifteen times as long as ours and not the least cloud to moderate heat? He fancies that for this reason Nature has made great cavities in the Moon, discernible with telescopes—not mountains but wells or vaults in the middle of a plain. Who knows but the Moon’s inhabitants, continually broiled by the Sun’s excessive heat, retire into those great wells; perhaps they live nowhere else and build cities there, as in the ruins of Old Rome the underground part was almost as large as that above ground. Take that part away and the rest would remain like one of these lunar towns; the whole people reside in wells.
Venus’s Gallants and Mercury’s Bedlam
Venus certainly turns on itself, though no one knows in what time, so its day’s length is unknown; its year is eight months because it circles the Sun in that time. Venus being forty times less than Earth, Earth appears to Venus-dwellers forty times bigger than Venus appears to us; and since the Moon is forty times lesser than Earth, the Moon seems to the inhabitants of Venus just the same magnitude as Venus seems to us. The Countess concludes Earth is too big to be the mother of love or shepherd’s star to Venus; that name suits only a little brisk airy planet, bright and shining like the goddess. The narrator exclaims the blessed Moon is happy to preside over the amours of Venus’s inhabitants, who must be masters of gallantry; the common people of Venus are all Celadons and Silvanders, their trivial discourse finer than any in Clelia; their climate inspires love, Venus being much nearer the Sun than Earth, receiving a more vigorous influence. The Countess guesses the inhabitants resemble the Moors of Granada—a little black people scorched with the Sun, witty, full of fire, amorous, inclined to music and poetry, inventing masks and tournaments for their mistresses. The narrator says Granada in all its glory was a perfect Greenland to it, and the gallant Moors, compared with that people, were as stupid as so many Lacedaemonians.
Being nearer the Sun, Mercury’s inhabitants are so full of fire they are absolutely mad; he fancies they have no memory, make no reflections, act by sudden starts and hazard; Mercury is the Bedlam of the universe. The Sun appears much greater to them; its light so vast that our most glorious day would be but a declining twilight; their accustomed heat so excessive they would be starved with cold in the Torrid Zone. Their year is three months; their day’s exact length is unknown because Mercury is so little and near the Sun, lost in his rays and hardly discovered by astronomers, who cannot observe how it moves on its center; but because it is so small they fancy it completes its motion in a little time. The Sun appears like a vast fiery furnace at a little distance, its motion prodigiously swift. This is better for them since they must long for night, during which Venus and Earth (appearing considerably big) give them light. The other planets beyond Earth toward the firmament appear less to them than to us, giving little or no light; the fixed stars likewise seem less, some totally disappearing—a great loss the narrator would esteem.
Wit Against Reason
The dialogue turns first on a quarrel between temperaments. People of wit and fire, the narrator observes, never reason; severe reasoners dismiss them as vulgar, and the witty retaliate by mocking the reasoners, since it seems a natural principle that every species despises what it lacks. He wishes the Countess had rallied the planetary inhabitants with her two witty friends, whose gift for raillery would have won their esteem without costing a single world. She asks whether truth should be sacrificed to a jest; he confesses little zeal for such truths and would gladly sacrifice them to the conveniences of company.
Why the Worlds Seem Improbable
He then explains why belief in inhabited planets is not received as probable as it deserves. Planets always appear to us as bodies emitting light, not as plains and meadows. We would readily grant that plains and meadows are inhabited, but luminous bodies seem implausible. Reason may insist there are fields and pastures there, but reason comes a day too late—a glance of the eyes has already done its work, and imagination cannot picture inhabitants of luminous bodies, so the shortest way is to believe there are none. He refuses to attack the formidable powers of sense and imagination on behalf of planetary people whose interests do not touch us, noting that men cannot easily be prevailed on to substitute reason for their eyes. Even reasonable people who accept a thousand demonstrations keep their first idea and seem to grant the opinion only as a courtesy, favoring it for the pleasure of its singularity.
Weighing Probability
The Countess asks whether this is not enough for a barely probable opinion. The narrator calls “probable” a very modest term. He compares the case to belief that Alexander ever existed: we have all the proofs we could desire in such a matter, though no mathematical demonstration, and we cannot see him. The planetary inhabitants are almost in the same case—we cannot see them nor insist on demonstration, but we have all proofs desirable: the entire resemblance of the planets to the inhabited Earth, the impossibility of conceiving another use for them, the fecundity and magnificence of Nature, and the regard to inhabitants’ necessities in giving moons to planets remote from the Sun and more moons to those more remote. Everything is to be said on one side and nothing on the other, unless one adopts the eyes and understanding of the vulgar. If the inhabitants really exist, they could not declare themselves by more sensible marks. She asks whether this is as certain as Alexander’s existence; he says not altogether, since though we have as many proofs as our situation allows, their number is not great.
The Minutes of Sentiment
The Countess protests that she cannot rank the inhabitants in her imagination—there is no absolute certainty, yet more than probability, and her notions are confounded. He counsels her not to be put out of conceit with them. Ordinary clocks show the hours, but those wrought with more art show the minutes; ordinary capacities sense the difference between ample probability and complete certainty, but only fine spirits discern exact proportions and mark the minutes in their sentiments. He places the planetary inhabitants a little below Alexander but above many points of history not so clearly proved. Loving order, she is obliged by this ranging of her ideas and asks why he did not take this care before; he answers that no great damage arises if she believes them a little more or less than they deserve.
The Earth’s Motion
The narrator then observes that she does not believe the Earth’s motion as fully as she ought, though she insists she firmly believes the Earth turns. He admits he has not given her the strongest reasons, having proved things only upon little engaging reasons adapted to her peculiar use rather than strong, solid arguments fit to attack a doctor in the science. She asks to be taken for a doctor from that moment and demands his additional demonstrations.
The Argument from Unequal Revolutions
The narrator owns the proof pleases him strangely, perhaps because he thinks it his own finding, yet it is so good and natural he must not presume to be its inventor; a learned man puzzled by it would be obliged to hold forth at large—the only method to confound a learned man. He argues we must grant that all celestial bodies turn round the Earth in twenty-four hours, or that the Earth turning on itself imparts this motion to them. That they really have this revolution in twenty-four hours has the least appearance in the world, though the absurdity does not presently appear. All planets make their great revolution about the Sun, unequal according to their distances—the most remote in a larger time, most agreeable to Nature—and the same order holds among secondary planets: the four moons of Jupiter and the five of Saturn make their circles in more or less time according as they are more or less remote. The planets also have motions on their own centers, likewise unequal; we cannot well tell whether this inequality proceeds from different magnitudes of the planets or the different swiftness of the particular vortices enclosing them and the liquid matters sustaining them, but the inequality is undoubted, and it is Nature’s general order that whatever is common to many things varies in some particulars.
The Countess interrupts, understanding that if the planets turned about the Earth they would do so in unequal times according to their distances, as they do about the Sun. The narrator confirms: their unequal distances with respect to the Earth, different magnitudes, and the different rapidity of the particular vortices enclosing them should produce differences in their pretended motion round the Earth as in all their other motions. The fixed stars, at prodigious distance and elevated above anything that can take a general motion round us—situated whence this motion should be much weakened—would there not be great appearance they did not turn at all about us in twenty-four hours, as the Moon so near us does?
The book’s central claim is not merely that the Earth moves but that the universe is crowded. Fontenelle builds the case by analogy and by a principle he calls Nature’s frugality: she is a great housewife, magnificent in design and thrifty in execution, always using what costs least. If the planets resemble the Earth—solid bodies receiving light from the Sun and reflecting it back—then the presumption is that they are inhabited. The argument from resemblance runs through every evening: the Moon is our St. Dennis, and we are Parisian cockneys who refuse to believe a town is inhabited because we cannot see its people from the towers of Notre-Dame. The narrator concedes that this is not mathematical demonstration, but he ranks the inhabitants of the planets a little below Alexander’s existence and above many points of history not so clearly proved.
What gives the book its charm is the way the argument is embodied in the two speakers. The Countess is no fool; she interrupts, objects, and often improves on the narrator’s fancies. When he multiplies worlds too liberally, she raises the objection that round vortices cannot all touch a single one—and he praises her for raising a doubt he cannot answer. She supplies the moral imagination he lacks: hearing that Mercury’s people must be mad with heat and Saturn’s phlegmatic with cold, she proposes that our Earth, placed in the middle, is composed of both extremes, a mixture of the several kinds found in the rest of the planets. The narrator, meanwhile, is a genial ironist who moralizes on self-love in the middle of a question of natural philosophy and admits he would sacrifice a truth to the conveniences of company. Their talk is the book’s real subject as much as astronomy is: the pleasure of speculation, the play of wit over demonstration.
The inhabitants themselves are drawn with deliberate lightness. The Moon’s people are not men—Nature’s face changes so much between here and China that the alteration between us and the Moon must be far greater. The people of Venus are all Celadons and Silvanders, black, witty, amorous, inclined to music and poetry; Mercury is the Bedlam of the Universe, its people full of fire and memoryless; Saturn’s are so phlegmatic that Cato would seem a merry-andrew among them. The Sun cannot be inhabited at all, since its inhabitants would be either blinded by its light or unable to receive it for want of distance. Fontenelle mingles true and false, as he warns, but the fancies are anchored in real questions: the length of days and years, the number of moons, the ring of Saturn performing the office of a continual moon, the great void space that serves as the apartment of comets.
The book’s most striking imaginative set-piece is the argument that one day there may be communication between Earth and the Moon. Before Columbus, the Americans hollowed tree-trunks with sharp stones and floated where wind and waves drove them; had anyone told them of ships that command the winds and carry thunder in their hands, they would not have believed it. So with flying: the art is newly invented, costs now and then a leg or an arm, and will improve by degrees until we may fly to the Moon—or the Moon’s people come to us. The narrator’s willingness to project a future of discovery, and his comparison of the undiscovered parts of the Earth to passengers in the prow and poop of the same vessel who never speak, gives the dialogues a speculative reach beyond their astronomy.
Fontenelle’s legacy is the form itself: the pluralist dialogue that makes difficult science conversable. He did not invent the idea of other worlds—Bruno and others had said it before—but he made it polite, witty, and available to readers who would never open a treatise. The book’s influence runs through the eighteenth century’s appetite for popular astronomy and beyond, to every later writer who has used a clever woman and a genial lecturer to carry a reader through the heavens. Its final lesson is less about the Moon than about the mind: we see all things through spectacles placed in our imagination, and the philosopher’s task is to notice the lenses.
