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3. It is not conceiveable for what use or benefit there should be any such element in that place; and certain it is, that nature does not do any thing in vain.
4. Betwixt two extremes there can be but one medium; and therefore between those two opposite elements of earth and water, it may seem more convenient to place only the air, which shall partake of middle qualities different from both.
5. Fire does not seem so properly and directly to be opposed to any thing as ice; and if the one be not an element, why should the other?
If you object, that the fire which we commonly use does always tend upwards; I answer, This cannot prove that there is a natural place for such an element, since our adversaries themselves do grant, that culinary and elementary fire are of different kinds. The one does burn, shine, and corrupt its subject; the other disagrees from it in all these respects. And therefore from the ascent of the one, we cannot properly infer the being or the situation of the other.
But for your farther satisfaction herein, you may peruse Cardan, Johannes Pena, that learned Frenchman the noble Tycho, with divers others who have purposely handled this proposition.
3. I inight add a third, viz. That there is no music of the spheres ; for if they be not solid, how can their motion cause any such sound as is conceived? I do the rather meddle with this, because Plutarch speaks as if a man might very conveniently hear that harmony, if he were an inhabitant in the moon. But I guess that he said this out of incogitancy, and did not well consider those necessary consequences which depend upon his opinion. However, the world would have no great loss in being deprived of this music, unless at some times we had the privilege to hear it*: then indeed Philo the Jew thinks it would save us the charges of diet, and we might live at
* De somniis.
an easy rate by feeding at the ear only, and receiving no other nourishment; and for this very reason, says he, was Moses enabled to tarry forty days and forty nights in the mount without eating any thing, because he there heard the melody of the heavens.--Risum teneatis. I know this music hath had great patrons, both sacred and profane authors, such as Ambrose, Bede, Boetius, Anselm, Plato, Cicero, and others; but because it is not now, I think, affirmed by any, I shall not therefore bestow either pains or time in arguing against it.
It may suffice that I have only named these three last, and for the two more necessary, have referred the reader to others for satisfaction. I shall in the next place proceed to the nature of the moon's body, to know whether that be capable of any such conditions, as may make it possible to be inhabited, and what those qualities are wherein it more nearly agrees with our earth.
sition, since it is a truth already agreed on by the general consent of the most and the best philosophers.
It is solid, in opposition to fluid, as is the air; for how otherwise could it beat back the light which it receives from the sun ?
But here it may be questioned, whether or no the moon bestow her light upon us by the reflection of the sun-beams from the superficies of her body, or else by her own illumination? Some there are who affirm this latter part. So Averroes *, Cælius Rhodiginus +, Julius Cæsar I, &c. And their reason is, because this light is discerned in many
+ Ant, lection. I. 20. c. 4.
* De cælo l. 2. com. 49.
De phænom. lunæ. c. 11.
places, whereas those bodies which give light by reflexion, can there only be perceived where the angle of reflexion is equal to the angle of incidence, and this is only in one place; as in a looking-glass, those beams which are re: flected from it, cannot be perceived in every place where you may see the glass, but only there where your eye is placed on the same line whereori the beams are reflected.
But to this I answer, That the argument will not hold of such bodies whose superficies is full of unequal parts and gibbosities, as the moon is. Wherefore it is as well the more probable as the more common opinion, that her light proceeds from both these causes, from reflexion and illumination ; nor doth ii herein differ from our earth, since that also hath some light by illumination: For how otherwise would the parts about us in a sun-shine day appear so bright, when as the rays of reflexion cannot enter into our eye?
For the better illustration of this, we may consider the several ways whereby divers bodies are enlightened. Either as water by admitting the beams into its substance; or as air and thin clouds, by transmitting the rays quite through their bodies; or as those things that are of an opacous natare, and smooth superficies, which reflect the light only in one place; or else as those things which are of an opacous nature, and rugged superficies, which by a kind of circumfluous reflexion, are at the same time discernible in many places, as our earth and the moon.
2. It is compact, and not a spungy and porous substance. But this is denied by Diogenes*, Vitelliot, and Reinoldus I, and some others, who held the moon to be of the same kind of nature as a pumice-stone; and this, say they, is the reason why in the sun's eclipses, there appears within her a duskish ruddy.colour, because the sun-beams being refracted in passing through the pores of her body, must necessarily be represented under such a colour.
+ Opt. I. 4.
* Plut. de pla. Phil. 1. 2. c. 13.
I Com. Purbac. Theo. p. 164. VOL. I.
But I reply, if this be the cause of her redness, then why doth she not appear under the same form when she is about a sextile aspect, and the darkened part of her body is discernible? for then also do the same rays pass through her, and therefore in all likelihood should produce the same effect ; and notwithstanding those beams are then diverted from vis, that they cannot enter into our eyes by a straight line, yet must the colour still remain visible in her body. And besides, according to this opinion, the spots would not always be the same, but diverse as the various distance of the sun requires. Again, if the sun-beams did pass through her, why then hath she not a tail (saith Scaliger *) as the comets? Why doth she appear in such an exact round? and not rather attended with a long flame, since it is merely this penetration of the sun-beams that is usually attributed to be the cause of beards in blazing stars.
3. It is opacous, not transparent or diaphanous like crystal or glass, as Empedocles thought t, who held the moon to be a globe of pure congealed air, like hail inclosed in a sphere of fire ; for then,
1. Why does she not always appear in the full? since, the light is dispersed through all her body?
2. How can the interposition of her body so darken the sunf, or cause such great eclipses as have turned day into night; that have discovered the stars, and frightened the birds with such a sudden darkness, that they fell down upon the earth? as it is related in divers histories. And therefore Herodotus telling of an eclipse which fell in Xerxes's time, describes it thus : ó y ENTHU TYY EX TS egeve edgyv e Qevis nu ş. The sun leaving his wonted seat in the heavens, vanished away: all which argues such a great darkness as could not have been, if her body had been perspicuous. Yet some there are who interpret all these relations to be hyperbolical expressions; and the noble Tycho thinks it naturally impossible that any eclipse should
Cause such darkness, because the body of the moon can never totally cover the sun. However, in this he is singular, all other astronomers (if I may believe Keplar) being on the contrary opinion, by reason the diameter of the moon does for the most part appear bigger to us than the diameter of the sun.
But here Julius Cæsar once more puts in to hinder our passage. The moon (saith he *) is not altogether opacous, because it is still of the same nature with the heavens, which are incapable of total opacity: and his reason is, because perspicuity is an inseparable accident of those purer bodies; and this he thinks must necessarily be granted; for he stops there, and proves no further ; but to this I shall defer an answer till he hath made up his argument.
We may frequently see, that her body does so eclipse the sun, as our earth doth the moon. And besides, the mountains that are observed there, do cast a dark shadow behind them, as shall be shewed afterwards t. Since then the like interposition of them both, doth produce the like effect, they must necessarily be of the like natures, that is, aliko opacous, which is the thing to be shewed; and this was the reason (as the interpreters guess) why Aristotle $ affirmed the moon to be of the earth's nature, because of their agreement in opacity; whereas all the other elements, save that, are in some measure perspicuous.
But the greatest difference which may seem to make our earth altogether unlike the moon, is, because the one is a bright body, and hath light of its own, and the other a gross dark body which cannot shine at all. It is requisite therefore that in the next place I clear this doubt, and shew that the moon hath no more light of her own than our earth.
* De phænom. lunæ, c. 11.
† Prop. 9.
In lib. de animalib.