Conversations on the Plurality of Worlds

by M. de Fontenelle

ADDITIONAL THOUGHTS IN CONFIRMATION OF THOSE IN THE PRECEDING CONVERSATIONS.—DISCOVERIES THAT HAVE BEEN LATELY MADE IN THE HEAVENS.

For a long time the Marchioness and I said nothing about the plurality of worlds, we had apparently forgotten that we had ever talked on the subject. I went one day to her house, and just as I entered, two men of some talents and celebrity were going out. You see, said she, what visitors I have had; I assure you they are gone away with a suspicion that you have turned my brain. I should be very proud of such an achievement answered I; it would shew my power, for I think one could not devise a more difficult undertaking. Well, replied she, I am afraid you have accomplished it. I don't know how it happened, but whilst my two friends, whom you met at the door, were here, the conversation turned on the plurality of worlds; perhaps they had an invidious design in directing it to that subject. I immediately told them all the planets were inhabited. One of them said he was certain I could not be of that opinion: in the most unaffected manner, I maintained my sincerity; he continued to think I was only feigning, and I believe he had too great a regard for me to admit the possibility of my having really adopted so extravagant an opinion. The other, from esteeming me less, did not doubt my veracity. Why have you made me obstinately adhere to sentiments which people who have the greatest friendship for me will not suffer themselves to believe me possessed with? But, madam, answered I, why did you maintain these opinions seriously, when talking with persons that I am sure would not gravely argue on any subject? Should we thus trifle with the inhabitants of the planets? Let us, who believe their existence, be content to remain a little select band, and not disclose our mysteries to the vulgar. Vulgar! exclaimed she; do you reckon those two men among the vulgar? They have good understandings, said I; but they never reason. Grave reasoners, who are austere people, would not hesitate to place them in that class. They however take their revenge by ridiculing the reasoners. We should if possible accommodate ourselves to persons of both characters; it would have been better to speak jestingly of the planetary inhabitants to such men as your two friends, since they are accustomed to pleasantry, than to enter on an argument, for which they have no talents. You would have retained their good opinion without depriving the planets of a single inhabitant. Would you have meanly sacrificed the truth? answered she. Where is your conscience? I must own, I replied, I have not much zeal for truths of this nature; I would readily forbear to maintain them if it suited my convenience.

The cause which prevents people from believing the planets to be inhabited is, that they appear to them only bodies placed in the heavens to give light, instead of globes consisting of meadows and fruitful countries. We readily believe that meadows and fields are inhabited, but it is thought ridiculous to assert that mere luminous bodies are. 'Tis in vain that reason informs us of fields in the planets; reason comes too late, the first coup-d'œil has impressed our minds before-hand, and this impression is not willingly parted with. The planets, 'tis said, are only luminous bodies; what sort of inhabitants then can they have? Our imaginations do not enable us to distinguish their figures, therefore it is the shortest way to deny their existence. Would you require me, for the sake of establishing the idea of these inhabitants, whose interest cannot be very dear to me, to attack all the powers of the senses and the imagination? Such an enterprize would demand a vast deal of courage. Men are not easily persuaded to see through their reason, rather than their eyes. Some few persons are rational enough to believe, after a thousand proofs have been given them, that the planets are worlds like ours, but they do not believe it in the same way they would do, if they had not seen them apparently so different; they always recur to the first idea they had formed, and can never wholly divest themselves of it. These people seem to condescend to our opinion, and only patronize it from a love of singularity.

Is not that enough, said she; for an opinion that is merely probable? You would be astonished, answered I, if I told you the word probable was too modest for the occasion. Is it merely probable that Alexander has been in existence? No, you consider it certain; and what is the ground of your certainty? Is it not that you have had every proof that such a subject requires, and that no circumstance leads you to doubt the fact? You have never seen Alexander, nor have you any mathematical demonstration of his existence. What would you say if this were the case with respect to the inhabitants of the planets? We cannot shew them to you, nor can you require us to demonstrate their being, in a mathematical way; but you have all the evidence that can be desired: the entire resemblance between the planets and the inhabited earth; the impossibility of imagining any other use for which they could be created; the fruitfulness and magnificence of nature; the attention she seems to have paid to the wants of their inhabitants, such as giving moons to those planets that were very remote from the sun, and the greatest number of moons to the most distant: and it is an important consideration that every thing is on that side of the question, without any objections to counterbalance it; you cannot for a moment doubt unless you resume the vulgar mode of seeing and thinking. In fact it is impossible to have more evidence, and evidence of a more determinate kind; how then can you treat this opinion as a mere probability? But do you think, said she, I can feel as certain that the planets are inhabited, as that Alexander has been in existence? By no means, I replied; for although, on the subject we are speaking of we have as many proofs as in our situation we can receive, yet these proofs are not numerous. I protest, exclaimed she, I'll renounce these planetary inhabitants, for I don't know whether to believe there are any or not—it is not certain, yet it is more than possible—I am quite perplexed. Do not be discouraged, madam, I replied. Clocks that are made in the most common manner shew the hour; those only that are made with more exquisite art, indicate the minutes; in like manner common minds see a great difference between probability and absolute certainty; but it is only superior understandings that ascertain the degrees of certainty or of probability, and who, if I may use the expression, can tell the minutes as well as the hours. Place the inhabitants of the planets a little below Alexander in point of certainty, but above a vast number of historical relations which are not entirely proved; I think that is their proper place. I love order, said she, you do me a kindness in giving arrangement to my ideas: why did you not do this before? Because, answered I, whether you attribute to this idea a little more, or a little less certainty than it possesses is not of much consequence. I am certain you do not feel so assured as you ought to do of the earth's motion: are you the less happy on that account? Oh! as to that opinion, I am sure I do my duty; you have no right to complain of me, for I firmly believe that the earth turns. Yet I have not given you the most convincing proof of it, answered I. You use me very ill, said she, to make one believe things without sufficient reason; am I unworthy to hear the best arguments? I wished to prove my opinions, I replied, by easy, entertaining arguments; would you have had me make use of such solid, sturdy ones as I should have attacked a doctor with? Certainly, said she; now fancy me a doctor, and let me have this new proof of the earth's motion.

With all my heart, answered I; it is this, and I am vastly pleased with it, because I think I found it out myself; but it is so good and so natural that I can hardly hope to have been the inventor. I am sure an obstinate learned man who wished to oppose it, would be forced to talk a great deal on the occasion; and that is the only way in which a scholar can be overcome. It is evident either that all the heavenly bodies go round the earth in four-and-twenty hours, or the earth, turning on her axis, only imagines the motion in them. It is the most improbable thing in the world that they should in reality go round the earth in that short space of time, though we are not at first aware of the absurdity of such an opinion. All the planets certainly revolve round the sun: but these revolutions are unequal from the unequal distances at which they are placed from the sun: the most remote, as we might naturally suppose, take a longer time than the rest. This order is observed even in the satellites that go round a large planet. Jupiter's four moons, and the five belonging to Saturn, require a longer or shorter time to move round their planet according to their distance from it. It is further ascertained that the planets have a rotation on their own axis; the time of this is likewise unequal; we cannot tell the cause of such inequality, whether it depends on the different size, or the degree of solidity of the planets, or on the different degrees of rapidity of the vortices in which they are enclosed, and the liquid matter by which they are carried along;[57] this inequality however is certain, and in general we find that the order of nature is such as to admit of particular variations in things that are regulated by the same rules.

[57] We can assign no reason; the irregularity depends on the original cause, whatever that cause may be, which at first determined their motions.

I understand, said the Marchioness; I am quite of your opinion; if the planets moved round the earth, the time employed by each would be different, according to their various distances, as is the case in their revolutions round the sun: is not that what you mean? Precisely so, madam, answered I; their unequal distances from the earth would produce an inequality in their revolutions round her: and the fixed stars, being so extremely remote from us, so far beyond all that could have a general movement round us, at least situated in a place where such a motion must be very feeble, is there any probability of their revolving round us in four-and-twenty hours, like the moon which is so near to us? Ought not the comets likewise which do not belong to our vortex, which have such irregular courses, and such different degrees of swiftness, to be exempted from performing this daily circle round our world? No, planets, fixed stars, and comets too, must all turn round the earth! Were there but a few minutes difference in the time of their revolutions we might be satisfied with it; but they are all exactly equal, never varying in the slightest degree; surely this is a suspicious circumstance.

Oh! replied the Marchioness, I could venture to say this exactitude existed only in our imaginations. I am glad that any thing inconsistent with the genius of nature, which this equality in so many moving bodies would be, should depend on our motion, and she, even at our expense, be free from the charge of inconsistency. For my part, said I, I dislike a perfect regularity, and I don't approve of the earth's turning every day on her axis in exactly twenty-four hours; I am disposed to think the time varies. Varies! she exclaimed; do not our clocks shew that it is always equal? Oh! replied I, I don't depend on clocks, they cannot always be perfectly right; and should they be so, and sometimes shew that the earth has made a longer or shorter tour in four-and-twenty hours than usual, it would be thought that we ought rather to suspect them of being wrong than to attribute any irregularity to the revolutions of the earth. That is paying an extravagant respect to her, I should depend no more on the earth than on a clock; the one might be put out of sorts almost by the same causes as the other, only I think it would take longer time to produce a sensible irregularity in the earth; that is the only advantage I should allow her to have over a clock. Might not the earth by degrees get nearer to the sun, and then, finding herself in a situation where the matter was agitated with greater violence, perform her motion on her axis, and her revolution round the sun, in a shorter time? In that case the years would be shorter, and the days too, but we should not perceive the difference, for we should still divide the year into three hundred and sixty-five days, and the days into twenty-four hours. So that without living longer than we do now, we should live a greater number of years: and on the contrary, if the earth were to remove farther from the sun, we should live fewer years, although our lives would be as long. In all probability, said she, if that were possible, a long succession of ages would make but a trifling difference. True, I replied; nature does nothing abruptly, her method is to effect every alteration by such gentle gradations that it is scarcely perceptible to us. We hardly observe even the changes of seasons; others that are produced much more slowly must in general escape our notice. Nevertheless every thing is subject to mutability; even a certain lady who has been seen, through telescopes, in the moon for about forty years, appears considerably older. She used to be rather handsome; now her cheeks are fallen away, her nose and chin are beginning to meet; in short all her charms are fled, and it is even feared that her life is near its close.[58]