Suppose ABCD to represent the appearance of the Moones body being in a sextile, you may see some brighter parts separated at a pretty distance from the other, which can bee nothing else but a reflexion of the Sunne-beames upon some parts that are higher then the rest, and those obscure gibbosities which stand out towards the enlightened parts must bee such hollow and deepe places whereto the rayes cannot reach, but when the Moone is got further off from the Sunne, and come to that fulnesse, as this line BD doth represent her under, then doe these parts also receive an equall light, excepting onely that difference which doth appeare betwixt their sea and land. And if you do consider how any rugged body would appeare, being enlightned, you would easily conceive that it must necessarily seeme under some such gibbous unequall forme, as the Moone is here represented. Now for the infallibility of these appearances, I shall referre the reader to that which hath beene said in the 6th Proposition. But _Cæsar la Galla_ affirmes, that all these appearances may consist with a plaine superficies, if wee suppose the parts of the body to be some of them, _Diaphanous_, and some opacous; and if you object that the light which is conveyed to any diaphanous part in a plaine superficies must be by a continued line, whereas here there appeare many brighter parts among the obscure at some distance from the rest. To this he answers, it may arise from some secret conveyances and channels within her body, that doe consist of a more diaphanous matter which being covered over with an opacious superficies, the light passing through them may breake out a great way off, whereas the other parts betwixt may still remaine darke. Just as the River _Arethusa_ in _Sicile_ which runnes under ground for a great way, and afterwards breakes out againe. But because this is one of the chiefest fancies whereby hee thinkes hee hath fully answered the arguments of this opinion, I will therefore set downe his answere in his owne words, lest the Reader might suspect more in them then I have expressed.[1] _Non est impossibile cœcos ductus diaphani & perspicui corporis, sed opacâ superficie protendi, usque in diaphanam aliquam ex profundo in superficiem, emergentem partem, per quos ductus lumen longo postmodum interstitio erumpat, &c._