Part 12

"I believe that this globe of earth and water would appeare like some great Starre to any one, who should looke upon it from the moone."

Now this could not be, nor could it shine so remarkably, unlesse the beames of light, were reflected from it. And therefore the same Fromondus expresly holds, that the first region of ayre is there terminated, where the heate caused by reflexion begins to languish, whereas the beames themselves doe passe a great way further. The chiefe argument which doth most plainely manifest this truth, is taken from a common observation which may be easily tryed.

If you behold the Moone a little before or after the conjunction, when she is in a sextile with the Sunne, you may discerne not onely the part which is enlightned, but the rest also to have in it a kind of a duskish light, but if you chuse out such a scituation, where some house or chimney (being some 70 or 80 paces distant from you) may hide from your eye the enlightned hornes, you may then discerne a greater and more remarkeable shining in those parts unto which the Sunne beames cannot reach; nay there is so great a light, that by the helpe of a good perspective you may discerne its spots. Inso much that Blancanus the Jesuite speaking of it sayes

Hæc experientia ita me aliquando fefellit, ut in hunc fulgorem casu ac repente incidens, existimarim novo quodam miraculo tempore adolescentis lunæ factum esse plenilunium.

"This experiment did once so deceive mee, that happening upon the sight of this brightnesse upon a sudden, I thought that by some new miracle the Moone had beene got into her full a little after her change."

But now this light is not proper to the Moone, it doth not proceed from the rayes of the Sunne which doth penetrate her body, nor is it caused by any other of the Planets and Starres. Therefore it must necessarily follow, that it comes from the earth. The two first of these I have already proved, and as for the last, it is confidently affirmed by Cælius,

Quod si in disquisitionem evocet quia, an lunari syderi lucem foenerent planetæ item alii, asseveranter astruendum non foenerare.

"If any should aske whether the other Planets lend any light to the Moone; I answer they doe not." True indeed, the noble Tycho discussing the reason of this light attributes it to the Planet Uenus, and I grant that this may convey some light to the Moone; but that it is not the cause of this whereof wee now discourse, is of itselfe sufficiently plaine, because Uenus is sometimes over the Moone, when as shee cannot convey any light to that part which is turned from her.

It doth not proceede from the fixed starres, for then it would retaine the same light in eclipses, whereas the light at such times is more ruddy and dull. Then also the light of the Moone would not be greater or lesser, according to its distance from the edge of the earths shadow, since it did at all times equally participate this light of the starres.

Now because there is no other body in the whole Universe, save the earth, it remaines that this light must necessarily be caused by that which with a just gratitude repaies to the Moone, such illumination as it receives from her.

And as loving friends equally participate of the same joy and griefe, so doe these mutually partake of the same light from the Sunne, and the same darkenesse from the eclipses, being also severally helped by one another in their greatest wants: For when the Moone is in conjunction with the Sunne, and her upper part receives all the light, then her lower Hemispheare (which would otherwise be altogether darke) is enlightened by the reflexion of the Sunne beames from the earth. When these two planets are in opposition, then that part of the earth which could not receive any light from the Sunne beames, is most enlightened by the Moone, being then in her full; and as she doth most illuminate the earth when the Sunne beames cannot, so the gratefull earth returnes to her as great, nay greater light when shee most wants it; so that alwaies that visible part of the Moone which receives nothing from the Sunne, is enlightened by the earth, as is proved by Galilæus, with many more arguments, in that Treatise which he calls Systema mundi. True indeed, when the Moone comes to a quartile, then you can neither discerne this light, nor yet the darker part of her body, but the reason is, because of the exuperancy of the light in the other parts. Quippe illustratum medium speciem recipit valentiorem, the clearer brightnesse involves the weaker, it being with the species of sight, as it is with those of sound, and as the greater noise drownes the lesse, so the brighter object hides that which is more obscure. But they doe alwaies in their mutuall vicissitudes participate of one anothers light; so also doe they partake of the same defects and darknings, for when our Moone is eclipsed, then is their Sunne darkened, and when our Sunne is eclipsed, then is their Moone deprived of its light, as you may see affirmed by Mæslin.

Quod si terram nobis ex alto liceret intueri, quemadmodum deficientem lunam ex longinquo spectare possumus, videremus tempore eclipsis solis terræ aliquam partem lumine solis deficere, eodem planè modo sicut ex opposito luna deficit,

"If wee might behold this globe of earth at the same distance as we doe the Moone in her defects, wee might discerne some part of it darkened in the Sunnes eclipses, just so as the Moone is in hers."

For as our Moone is eclipsed by the interposition of our earth, so is their Moone eclipsed by the interposition of theirs. The manner of this mutuall illumination betwixt these two you may plainly discerne in this Figure following.

Where A represents the Sun, B the Earth, and C the Moone; Now suppose the Moone C to be in a sextile of increase, when there is onely one small part of her body enlightened, then the earth B will have such a part of its visible Hemispheare darkened, as is proportionable to that part of the Moone which is enlightened; and as for so much of the Moone, as the Sun beames cannot reach unto, it receives light from a proportionall part of the earth which shines upon it, as you may plainly perceive by the Figure.

You see then that agreement and similitude which there is betwixt our earth and the Moone. Now the greatest difference which makes them unlike, is this, that the Moone enlightens our earth round about, whereas our earth gives light onely to that Hemispheare of the Moone which is visible unto us, as may be certainly gathered from the constant appearance of the same spots, which could not thus come to passe, if the Moone had such a diurnall motion about its own axis, as perhaps our earth hath. And though some suppose her to move in an epicycle, yet this doth not so turne her body round, that we may discerne both Hemispheares, for according to that hypothesis, the motion of her eccentrick, doth turne her face towards us, as much as the other doth from us.

But now if any question what they doe for a Moone who live in the upper part of her body? I answer, the solving of this is the most uncertaine and difficult thing that I know of concerning this whole matter. But yet I will give you two probable conjectures.

1. Perhaps, the upper Hemispheare of the Moone doth receive a sufficient light from those planets about it, and amongst these Venus (it may be) bestowes a more especiall brightnesse, since Galilæus hath plainly discerned that she suffers the same increase and decreases, as the Moone hath, and 'tis probable that this may be perceived there without the help of a glasse, because they are farre neerer it than wee. When Venus (saith Keplar) lies downe in the Perige or lower part of her supposed Epicycle, then is she in conjunction with her husband the Sunne, from whom after she hath departed for the space of ten moneths, shee gets plenum uterum, and is in the full.

But you'll reply, though Venus may bestow some light when she is over the Moone, and in conjunction, yet being in opposition, she is not visible to them, and what shall they then doe for light?

I answer, then they have none: nor doth this make so great a difference betwixt those two Hemispheares as there is with us, betwixt the places under the poles, and the line, but if this bee not sufficient, then I say in the second place that

2. Perhaps there may be some other enlightened body above the Moone which we cannot discerne, nor is this altogether improbable because there is almost the like observed in Saturne, who appeares through this glasse with two lesser bodies on each side, which may supply the office of Moones, unto each hemispheare thus:

o O o

So in this world also there may be some such body, though wee cannot discerne it, because the Moone is alwaies in a streight line, betwixt our eye and that. Nor is it altogether unlikely that there should bee more moones to one Orbe, because Jupiter also is observed to have foure such bodies that move round about him.

But it may seeme a very difficult thing to conceive, how so grosse and darke a body as our earth, should yeeld such cleare light as proceedes from the Moone, and therefore the Cardinall de Cusa (who thinkes every Starre to be a severall world) is of opinion that the light of the Sunne is not able to make them appeare so bright, but the reason of their shining is, because wee behold them at a great distance through their regions of fire which doe set a shining lustre upon those bodies that of themselves are darke.

Vnde si quis esset extra regionem ignis, terra ista in circumferentia suæ regionis per medium ignis lucida stella appareret.

"So that if man were beyond the region of fire, this earth would appear through that as a bright Starre."

But if this were the onely reason then would the Moone bee freed from such increases and decreases as shee is now lyable unto.

Keplar thinkes that our earth receives that light whereby it shines from the Sunne, but this (saith he) is not such an intended cleare brightnesse as the Moone is capable of, and therefore hee guesses, that the earth there is of a more chokie soyle like the Ile of Creete, and so is better able to reflect a stronger light, whereas our earth must supply this intention with the quantity of its body, but this I conceive to be a needlesse conjecture, since our earth if all things were well considered, will be found able enough to reflect as great a light. For