Latin has two common words for "light": lux and lumen.

What are the differences between these two words? Are there any contexts in which one would be appropriate while the other would not? It would be particularly illuminating (pun intended) if there were a passage in which the two were used side-by-side in contrast to each other.

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    At some point I'll do the research, but I do know that Robert Grosseteste (an early 13th c. English philosopher) has a lot to say about lux and lumen, and I believe he develops an explicit contrast.
    – brianpck
    Commented May 15, 2020 at 16:48

2 Answers 2


I did a search for lux and lumen in the Latin dictionaries at Latinitium https://www.latinitium.com/latin-dictionaries?t=lsn27193,do307 They seem to overlap in meaning, with lux being used more often for daylight and lumen being used more often for lamps and torches. The entry for Doderlein at the bottom of the page has examples where they are used in contrasting ways, and says

Lumen (λευσσόμενον) is a luminous body, like φέγγος; lux (λευκή) a streaming mass of light, like φάος. Cic. Fin. iii. 14, 45. Ut obscuratur et offunditur luce solis lumen lucernæ. Curt. viii. 2, 21. Sed aditus specus accipit lucem; interiora nisi allato lumine obscura sunt. Cic. Acad. iv. 8, 28. Si ista vera sunt, ratio omnis tollitur quasi quædam lux lumenque vitæ; that is, reason alone is in itself bright and light, and at the same time spreads brightness and light over life. Also, in a figurative sense, lumen denotes distinction, lux only clearness. Cicero (Man. 5.) calls Corinth, Græciæ totius lumen, but Rome (Catil. iv. 6.) Lucem orbis terrarum; Corinth is compared to a glimmering point of light; Rome is distinguished as that city in comparison with which all other cities lie in darkness. (ii. 66.)


Also, the Nicean creed uses Lumen instead of Lux (Deum de Deo, Lumen de Lumine) to refer to the light of God, implying a more metaphorical meaning to Lumen, rather than the strict sense of light.

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    Welcome to the site and thanks for the nice answer! It has already earned you enough reputation to allow you to vote up any questions and answers you like on the site.
    – Joonas Ilmavirta
    Commented May 15, 2020 at 15:40
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    I think you're on the right track--though Christ's words in the Gospel are "Ego sum lux mundi," so lux can also have a metaphorical meaning.
    – brianpck
    Commented May 15, 2020 at 16:46
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    cf. dixitque Deus fiat lux et facta est lux.
    – Alex B.
    Commented May 18, 2020 at 2:41

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