Archimedes Texts

76
Quadrature, the same appears very weak, because it continually
loseth more and more of the view of the luminous part of the
Earth: and yet it should succeed quite contrary, if that light were
its own, or communicated to it from the Stars; for then we should
see it in the depth of night, and in so very dark an ambient.

*By the Moons two
Quadratures you
are to understand
its first and last
quarters, as A
strologers call them

SIMPL. Stay a little; for I just now remember, that I have
read in a little modern tract, full of many novelties; “That this
secondary light is not derived from the Stars, nor innate in the
Moon, and least of all communicated by the Earth, but that it is

received from the same illumination of the Sun, which, the sub
stance of the Lunar Globe being somewhat transparent, pene
trateth thorow all its body; but more livelily illuminateth the
superficies of the Hemisphere exposed to the rays of the Sun:
and its prosundity imbuing, and (as I may say) swallowing that
light, after the manner of a cloud or chrystal, transmits it, and
renders it visibly lucid. And this (if I remember aright) he
proveth by Authority, Experience and Reason; citing Cleomedes,
Vitellion, Macrobius, and a certain other modern Author: and
adding, That it is seen by experience to shine most in the days
nearest the Conjunction, that is, when it is horned, and is chiefly
bright about its limb. And he farther writes, That in the Solar
Ecclipses, when it is under the Discus of the Sun, it may be seen
translucid, and more especially towards its utmost Circle. And
in the next place, for Arguments, as I think, he saith, That it not
being able to derive that light either from the Earth, or from the
Stars, or from it self, it necessarily follows, that it cometh from
the Sun. Besides that, if you do but grant this supposition, one
may easily give convenient reasons for all the particulars that
occur. For the reason why that secundary light shews more
lively towards the outmost limb, is, the shortness of the space
that the Suns rays hath to penetrate, in regard that of the lines
which pass through a circle, the greatest is that which passeth
through the centre, and of the rest, those which are farthest from
it, are always less than those that are nearer. From the same
principle, he saith, may be shewn why the said light doth not
much diminish. And lastly, by this way the cause is assigned
whence it comes, that that same more shining circle about the
utmost edge of the Moon, is seen at the time of the Solar Ec
clipse, in that part which lyeth just under the Discus of the Sun,
but not in that which is beside the Discus: which happeneth
because the rays of the Sun pass directly to our eye, through the
parts of the Moon underneath: but as for the parts which are
besides it, they fall besides the eye.”

SALV. If this Philosopher had been the first Author of this o
pinion, I would not wonder that he should be so affectionate to it,