Here is another one.
At issue in this present foray is a passage on Scripture from Institutes 2.4.6:
Scriptura seipsam Divinam probat, non modo authoritative et per modum argumenti inartificialis seu Testimonii, quando se θεόπνεῦστον vocat; quod licet bene usurpetur adversus Christianos, qui eam se recipere profitentur, non potest tamen urgeri adversus alios qui eam rejiciunt: Sed ratiocinative argumento artificiali, ex Notis quas Scripturae Deus impressit, quae indubitata prae se ferunt Divinitatis argumenta. Nam ut opera Dei incomparabilem Opificis sui praestantiam veluti oculis conspiciendam certis characteribus exhibent, et ut Sol propria luce innotescit: Ita voluit in Scriptura, quae est ἀποῤῥοη Patris luminum et Solis justitiae, fulgere varios divinitatis radios quibus se cognoscendam praebeat.
Here is the standard (and only) published English translation:
The Bible proves itself divine, not only authoritatively and in the manner of an artless argument or testimony, when it proclaims itself God-inspired (theopneuston). Although this may be well used against those Christians who profess to believe it, yet it cannot be employed against others who reject it. The Bible also proves itself divine ratiocinatively by an argument artfully made (artificiali) from the marks which God has impressed upon the Scriptures and which furnish indubitable proof of divinity. For as the works of God exhibit visibly to our eyes by certain marks the incomparable excellence of the artificer himself and as the sun makes himself known by his own light, so he wished in the Bible (which is the emanation [aporroe] from the Father of lights and the Sun of righteousness) to send forth different rays of divinity by which he might make himself known. (tr. G.M. Giger)
This translation is in some ways fine, but in one particular respect is not very illuminating: I’m not sure that what Turretin is doing with opposition of argumenti inartificialis and argumento artificiali is clear. The adjectives inartificialis and artificialis are not all that common, especially in classical Latin, and they have, I think, a particular semantic content when used together. I’m almost certain Turretin is thinking here of a passage at the beginning of Book 5 of Quintilian’s Institutio Oratoria, or something very like it, which in turn relies on a distinction of Aristotle’s. First, Quintilian:
ac prima quidem illa partitio ab Aristotele tradita consensum fere omnium meruit, alias esseprobationes, quas extra dicendi rationem acciperet orator, alias, quas ex causa traheret ipse et quodammodo gigneret. ideoque illas ἀτέχνους, id est inartificiales, has ἐντέχνους, id est artificiales,vocaverunt.
To begin with it may be noted that the division laid down by Aristotle has met with almost universal approval. It is to the effect that there are some proofs adopted by the orator which lie outside the art of speaking, and others which he himself deduces or, if I may use the term, begets out of his case. The former therefore have been styled ἄτεχνοι or inartificial proofs, the latter ἔντεχνοι or artificial. (tr. H.E. Butler)
As the note in the link points out, Quintilian refers to Aristotle, Rhetoric 1.2.2. So, Aristotle:
As for proofs, some are artificial, others inartificial. By the latter I understand all those which have not been furnished by ourselves but were already in existence, such as witnesses, tortures, contracts, and the like; by the former, all that can be constructed by system and by our own efforts. Thus we have only to make use of the latter, whereas we must invent the former. (tr. J.H. Freese)
The distinction is one between proofs supplied by the art of argument, proceeding according to the rules of argument, and proofs that are not constructed in that way, but are rather already to hand–“there,” as it were. An argument that is artificialis follows the rules of the art of argument; one that is inartificialis proceeds in a different way. In the particular passage of Turretin under discussion, Scripture’s testimony about itself is of the latter kind: it is just “there,” not a conclusion reached by an orderly, ruled process of reasoning.
Here is my take on the passage, which I hope brings out his meaning more distinctly even as it avails itself of a sort of paraphrastic gloss. That mode can better serve the transmission of sense in certain instances where a “word-for-word” rendering, putatively “literal,” would yield a significant semantic depletion.
Scripture shows itself to be divine, not only authoritatively and through the mode of proof that does not make use of the rules of the art of argument, or, [through the mode] of testimony, when it calls itself God-breathed (θεόπνεῦστον) (which, although the mode is put to good use against Christians, who profess that they receive it [as divine], is nevertheless unable to be brought to bear against others, who reject it); but also through the process of reasoning, by means of proof that does make use of the rules of the art of argument –[namely,] from the marks that God has impressed upon Scripture, which put forward undoubted proofs of its divinity. For as the works of God display by sure marks the incomparable excellence of their maker, in order that it may be seen as it were by the eyes, and as the sun becomes known by its own light, so [God] wished that in Scripture, which is the emanation of the Father of lights and the Sun of righteousness, various rays of divinity shine forth, in order that by them he might offer himself to be known.