Part 10 (1/2)

[Sidenote 1: _Progym. 1._]

[Sidenote 2: _l. 20. c. 5._]

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 partic.i.p.ate 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 grat.i.tude repaies to the Moone, such illumination as it receives from her.

And as loving friends equally partic.i.p.ate 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 _Galilaeus_, 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 ill.u.s.tratum medium speciem recipit valentiorem_,[1] 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 partic.i.p.ate 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 _Maeslin_.[2]

_Quod si terram n.o.bis ex alto liceret intueri, quemadmodum deficientem lunam ex longinquo spectare possumus, videremus tempore eclipsis solis terrae aliquam partem lumine solis deficere, eodem plane 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.

[Sidenote 1: _Scal. exerc. 62._]

[Sidenote 2: _Epit. Astro. l. 4. part. 2._]

[Ill.u.s.tration as described in text: sun, crescent moon and gibbous earth]

Where A represents the Sun, B the Earth, and C the Moone; Now suppose the Moone C to be in a s.e.xtile 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 s.h.i.+nes 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 pa.s.se, 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 _Galilaeus_ 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 gla.s.se, 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 s.p.a.ce 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 gla.s.se 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_[1] (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 s.h.i.+ning is, because wee behold them at a great distance through their regions of fire which doe set a s.h.i.+ning l.u.s.tre upon those bodies that of themselves are darke.

_Vnde si quis esset extra regionem ignis, terra ista in circ.u.mferentia suae 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.