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Is there any Roman or Latin writer person before 2nd-century AD who wrote moon does not have its own light but got it from Sun like the moon is a mirror which reflects sunlight, I know about Cicero ( Roman statesman ) and De architectura Book by Vitruvius, but Cicero doesn't say its reflected light but say sunlit moon by its ray and in Virtruvius book word "non" is not there (see this post), Reason for this post is In De architectura Virtruvius writes Moon does not have it's own is not secrete but the word "non" for moonlight is missing in original text and it's interpolated by the scholar.

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    The way Vitruvius mentioned this ( mentioning this explanation as second, and using non enim latet (translated there: "indeed it is no secret" - or even stronger: [Samus explanation cannot be right (hence it urged another explanation) ] for it is clear that ... ) is strongly suggestive (IMO) that that was the prevalent explanation in his time. Now, V clearly described two opposing views. ("rationes varietatis disciplinis de eadem reliquit" [Aristarchus] ); the first was that Luna has its own light (only half of the ball though) and this of Aristarchus.
    – d_e
    Aug 7 at 8:09
  • Abhishek: To add on to d_e, you can read more about Aristarchus's views here: worldhistory.org/Aristarchus_of_Samos
    – cmw
    Aug 7 at 14:30
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    Also, the manuscript of Vitruvius is not the original text. It's a much, much later copy of a copy of a copy.
    – cmw
    Aug 7 at 14:31
  • I meant Berosus explanation cannot be right
    – d_e
    Aug 7 at 14:53
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    @d_e: OK, interesting. I do think Cicero and Vitruvius could constitute a good answer. What the asker wants is not always the only way in which an answer can be good! Besides, he may very well be interested in this if you make a case that Cicero and/or Vitruvius are indeed good sources saying that the moon's light is reflective.
    – Cerberus
    Aug 7 at 18:16

2 Answers 2

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  1. For the record, here is the quote from Cicero (De Natuara Deorum):

ipse sol mundum omnem sua luce compleat, ab eoque luna inluminata graviditates et partus adferat maturitatesque gignendi.

and the sun itself fills all the world with light, and also illuminates the moon, which is the source of conception and birth and of growth and maturity.

In principle, I think it is not so rigorous strategy to learn what the ancients (and even modern people) thought on scientific things when they spoke about something which is not scientific treatise/history about the issue. Writers and speakers have some freedom, as we say even today that the Sun, Moon and others rise and set -- as if they are moving - but as most of us know (and knew also thousands of years ago) they are not really moving but their daily motion is due to the Earth rotation.

After saying that, if one is pushed to form a judgment on this passage from Cicero - be it even an alien who knows nothing about the Sun and the Moon - his guess would be that this implies that the Moon - just like other objects - is not illuminated by her own force.

  1. My understanding that the passage from De architectura by Vitruvius cannot be possibly comprehended in another way but to accept he brings the notion that the Moon reflects the Sun's light. That we can say by several arguments:
  • He brings the explnation of Aristarchus for the moon phases. we can read that this astronomer believed the Moonlight is a reflection of the light from the Sun. Vit thus writes: Uti autem Aristarchus Samius mathematicus vigore magno rationes varietatis disciplinis de eadem reliquit (= But Aristarchus of Samos, a mathematician of great powers, has left a different explanation in his teaching on this subject, as I shall now set forth. [Morris Hicky Morgan])
  • Even without knowing the above point, Virtruvius clearly described two opposing views ("rationes varietatis disciplinis de eadem reliquit" [Aristarchus]); first he presents the explanation of Berosus that included the idea that the Moon is a ball half-lit (BTW: Berosus should have some trouble in explaining Lunar eclipse where it is clear the half that should be lit is very weak); then he presents the view of Aristarchus. As we said, the views must be contrasted somehow - and this in that the Moon does not have her own light - but her light is a reflection (sed esse speculum); it is right that the in the text, which we currently hold, the word non is missing but it must be there IMO. (I can even spare the scribe because Vit starts this very sentence with negative non enim latet from there the road for scribe mistake is easier).
  • One can even make the argument that those different views are not even presented equally - but the author strongly leans towards Aristarchus, in his language he says it is "indeed not secret" (non enim latet) that the Moon reflects the Sun's light. But this is speculation on my side.
  1. I have found yet another reference by Pliny the Elder in his Natural History

utroque enim habitu plena est, ut saepius diximus, sed interlunio omne lumen quod a sole accepit caelo regerens.

for the moon is at the full at both phases, as we have often said, but at the point of its conjunction, it reflects back to the sky all the light it has received from the sun. (Loeb).

I'm not sure what Pliny is talking about in this passage from which this sentence is taken, but he says the Moon reflects (regerens) the light from the Sun back to the sky (i.e, to away from earth) in conjunction (i.e., in New Moon phase); it implies that the opposite happens in opposition (on Full Moon phase) where she reflects all the light to earth (rather than to the sky).


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The hypothesis that the moon reflects the light of the sun was well known to the ancient Greeks and Romans. Pliny the Elder describes the moon as reflecting sunlight, and also gives an explanation of lunar eclipses that clearly shows that he is aware that they are caused by the shadow of the earth blocking sunlight from reaching the moon. In fact, Pliny seems to incorrectly think that the stars also reflect the light of the sun; see this prior question: Use of "if" in a translation of Pliny the Elder's Natural History

Aside from the quotation in d_e's answer, here are other relevant parts of Pliny's Natural History Book II (AD 77) along with the translation by John Bostock (1855):

solis fulgore, ut reliqua siderum, regi, siquidem in totum mutuata ab eo luce fulgere, qualem in repercussu aquae volitare conspicimus

Bostock:

and that her brightness, as well as that of the other stars, is regulated by that of the sun, if indeed they all of them shine by light borrowed from him, such as we see floating about, when it is reflected from the surface of water.

Pliny:

ideo inaequali lumine adspici, quia, ex adverso demum plena, reliquis diebus tantum ex se terris ostendat, quantum a sole ipsa concipiat; in coitu quidem non cerni, quoniam haustum omnem lucis aversa illo regerat, unde acceperit.

Bostock:

On this account she appears with an unequal light, because being full only when she is in opposition, on all the remaining days she shows only so much of herself to the earth as she receives light from the sun. She is not seen in conjunction, because, at that time, she sends back the whole stream of light to the source whence she has derived it.

Pliny:

defectus autem suos et solis, rem in tota contemplatione naturae maxime miram et ostento similem, magnitudinum umbraeque indices exsistere. quippe manifestum est solem interventu lunae occultari lunamque terrae obiectu ac vices reddi, eosdem solis radios luna interpositu suo auferente terrae terraque lunae. hac subeunte repentinas obduci tenebras rursumque illius umbra sidus hebetari. neque aliud esse noctem quam terrae umbram, figuram autem umbrae similem metae ac turbini inverso, quando mucrone tantum ingruat neque lunae excedat altitudinem, quoniam nullum aliud sidus eodem modo obscuretur et talis figura semper mucrone deficiat. spatio quidem consumi umbras indicio sunt volucrum praealti volatus. ergo confinium illis est aëris terminus initiumque aetheris. supra lunam pura omnia ac diurnae lucis plena. a nobis autem per noctem cernuntur sidera, ut reliqua lumina e tenebris, et propter has causas nocturno tempore deficit luna.

Bostock:

But her eclipses and those of the sun, the most wonderful of all the phænomena of nature, and which are like prodigies, serve to indicate the magnitude of these bodies and the shadow which they cast. For it is evident that the sun is hid by the intervention of the moon, and the moon by the opposition of the earth, and that these changes are mutual, the moon, by her interposition, taking the rays of the sun from the earth, and the earth from the moon. As she advances darkness is suddenly produced, and again the sun is obscured by her shade; for night is nothing more than the shade of the earth. The figure of this shade is like that of a pyramid or an inverted top; and the moon enters it only near its point, and it does not exceed the height of the moon, for there is no other star which is obscured in the same manner, while a figure of this kind always terminates in a point. The flight of birds, when very lofty, shows that shadows do not extend beyond a certain distance; their limit appears to be the termination of the air and the commencement of the æther. Above the moon everything is pure and full of an eternal light. The stars are visible to us in the night, in the same way that other luminous bodies are seen in the dark. It is from these causes that the moon is eclipsed during the night.

Source of translation: The Natural History. Pliny the Elder. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855. From Perseus

This web page says that the argument for the sphericity of the earth based on the shape of its shadow in lunar eclipses (which implicitly relies on understanding that moonlight is reflected sunlight) was known to educated Greeks as far back as the 5th century B.C., the time when Empedocles and Anaxagoras lived.

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