Pulvis aut Favillae in 'Dust and Ashes' in the Book of Job?

Question

The famous phrase "Dust to Dust, Ashes to Ashes" does not come from the Bible but from the English Burial Service of the 1662 Book of Common Prayer, reading: "we therefore commit his body to the ground; earth to earth, ashes to ashes, dust to dust;" but the concept is mentioned in the Bible.

Genesis 3:19 reads: "In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return."

Vulgate: In sudore vultus tui vesceris pane donec revertaris in terram de qua sumptus es quia pulvis es et in pulverem reverteris

Hebrew: (...) כִּֽי־עָפָ֣ר אַ֔תָּה וְאֶל־עָפָ֖ר תָּשֽׁוּב

Septuagint: (...) ὅτι γῆ εἶ καὶ εἰς γῆν ἀπελεύσῃ

Genesis 18:27 reads: "And Abraham answered and said, Behold now, I have taken upon me to speak unto the Lord, which am but dust and ashes:"

Vulgate: Respondens Abraham ait quia semel coepi loquar ad Dominum meum cum sim pulvis et cinis

Hebrew: (...) וְאָנֹכִ֖י עָפָ֥ר וָאֵֽפֶר

Septuagint: (...) ἐγώ δέ εἰμί γῆ καί σποδός

Job 30:19 reads: "He hath cast me into the mire, and I am become like dust and ashes."

Vulgate: Conparatus sum luto et adsimilatus favillae et cineri

Hebrew: (...) כֶּעָפָ֥ר וָאֵֽפֶר

Septuagint: (...) γῇ καὶ σποδῷ μου ἡ μερίς

Job 42:6 reads: "Wherefore I abhor myself, and repent in dust and ashes."

Vulgate: Idcirco ipse me reprehendo et ago paenitentiam in favilla et cinere

Hebrew: (...) עַל־עָפָר וָאֵֽפֶר

Septuagint: (...) γῆν καὶ σποδόν

The original Hebrew Old Testament and subsequent Greek Septuagint uses the same words for Dust and Ashes consistently. For Dust: עָפָר and γῆ. For Ashes: אֵ֫פֶר and σποδός.

But, when the Bible was translated into the Latin Vulgate, we see two different words used for Dust: Pulvis and Favilla(e). [For Ashes they have used the same word consistently: Cinis]

As I read, Favilla(e) itself means Ashes (Short Definitions "cinders, hot ashes, glowing ashes, embers"), rather then "Dust/Soil/Earth". This definition in the entry for Cinis was particularly relevant:

I. In gen. (while favilla is usually the ashes that is light like dust, or is still glowing; cf.: “corporis favillam ab reliquo separantcinere,” Plin. 19, 1, 4, § 19: cinis e favillā et carbonibus ad calfaciendum triclinium illatis exstinctus et jam diu frigidus exarsit repente, Suet. Tib. 74), Lucr. 1, 872; cf. id. 1, 890, and 4, 927; Cato ap. Charis. p. 78 P.; Suet. Tib. 74; Col. 2, 15, 6; 11, 3, 28; 12, 22, 1; Hor. C. 4, 13, 28.—

And beloved Wiktionary summarises nicely, saying:

Usage Notes. The word cinis is used for cold, heavy ashes, while favilla is used for glowing, light ashes.

1. So can someone please explain to me why they have chosen to use "Favillae et Cinis" in the Book of Job, instead of "Pulvis et Cinis" (as in Genesis). What possible or probable reason would there be?

2. Is it a good choice? Or is it "wonky translation"?

3. Would "Pulvis et Favillae" be; a) a grammatically and conceptually correct alternative, and; b) better or worse then "Pulvis et Cinis"?

It's quite a different thing to repent 'in dust and ashes' and to repent 'in embers and ashes'... Ouch. But maybe there is some known figurative use of the word to explain this?

Note: Another example of the use of Favilla and Cinis both referring to ash is the Latin Hymn Dies Irae, which reads: "Dies iræ, dies illa Solvet sæclum in favilla, ... Cor contritum quasi cinis, ... Lacrimosa dies illa, Qua resurget ex favilla, Judicandus homo reus." ("The day of wrath, that day will dissolve the world in ashes, ... [my] heart crushed as ashes: ... Tearful [will be] that day, on which from the glowing embers will arise the guilty man who is to be judged.")

Edit: Just noting: Elsewhere in the Bible we see the Hebrew עָפָר (dry earth, dust) is translated into the Latin Terra and the Greek χοῦς (Eg. Genesis 2:7, Psalms 103:14, Ecclesiastes 3:1, etc.). But that seems quite proper and is hardly surprising like the use of Favillae instead of Terra/Pulvis in the Book of Job, so that is not a particular concern in this question.

Note: I've added a +50 Bounty

Answer 1

In Lewis and Short I find an interesting sub-meaning for "favilla":

B. Transf.: “salis,” powder of salt, Plin. 31, 7, 42, § 90.—*

But I can't actually find that in Pliny. favilla as powder would work, wouldn't it? Gaffiot gives the reference as Plin. 31, 90; and another non-cinder meaning in Propertius 1, 9.

Is Jerome always consistent in how he renders a word? Or is it simple variation?

Answer 2

Plater and White, in A Grammar of the Vulgate, after praising Jerome's "skillful and masterly workmanship" of his translation of the Hebrew, point out on Page 7, "Jerome has the tantalizing habit of translating the same Hebrew word by different Latin equivalents." Alas, I can find no entries for puluis or fauilla in the Latin index of that work.

Perhaps this diversity of words is purely a matter of style.