Chapter nine is about additional issues on the verity of scripture. There are 13 sections to this, and the authors note that is best to divide this into four parts. The first, Sections one and two, are general comments. His contempt for rhetorical flourish, in part one, is true, useful, and appropriate.
Rhetoric is to influence others, particularly the foolish. It is not truth, it is a toolkit.
1. IN vain were the authority of Scripture fortified by argument, or supported by the consent of the Church, or confirmed by any other helps, if unaccompanied by an assurance higher and stronger than human Judgment can give. Till this better foundation has been laid, the authority of Scripture remains in suspense. On the other hand, when recognising its exemption from the common rule, we receive it reverently, and according to its dignity, those proofs which were not so strong as to produce and rivet a full conviction in our minds, become most appropriate helps. For it is wonderful how much we are confirmed in our belief, when we more attentively consider how admirably the system of divine wisdom contained in it is arranged--how perfectly free the doctrine is from every thing that savours of earth--how beautifully it harmonises in all its parts--and how rich it is in all the other qualities which give an air of majesty to composition. Our hearts are still more firmly assured when we reflect that our admiration is elicited more by the dignity of the matter than by the graces of style. For it was not without an admirable arrangement of Providence, that the sublime mysteries of the kingdom of heaven have for the greater part been delivered with a contemptible meanness of words. Had they been adorned with a more splendid eloquence, the wicked might have cavilled, and alleged that this constituted all their force. But now, when an unpolished simplicity, almost bordering on rudeness, makes a deeper impression than the loftiest flights of oratory, what does it indicate if not that the Holy Scriptures are too mighty in the power of truth to need the rhetorician's art?
Hence there was good ground for the Apostle's declaration, that the faith of the Corinthians was founded not on "the wisdom of men," but on "the power of God," (1 Cor. 2:5), this speech and preaching among them having been "not with enticing words of man's wisdom, but in demonstration of the Spirit and of power," (1 Cor. 2:5). For the truth is vindicated in opposition to every doubt, when, unsupported by foreign aid, it has its sole sufficiency in itself. How peculiarly this property belongs to Scripture appears from this, that no human writings, however skilfully composed, are at all capable of affecting us in a similar way. Read Demosthenes or Cicero, read Plato, Aristotle, or any other of that class: you will, I admit, feel wonderfully allured, pleased, moved, enchanted; but turn from them to the reading of the Sacred Volume, and whether you will or not, it will so affect you, so pierce your heart, so work its way into your very marrow, that, in comparison of the impression so produced, that of orators and philosophers will almost disappear; making it manifest that in the Sacred Volume there is a truth divine, a something which makes it immeasurably superior to all the gifts and graces attainable by man.
2. I confess, however, that in elegance and beauty, nay, splendour, the style of some of the prophets is not surpassed by the eloquence of heathen writers. By examples of this description, the Holy Spirit was pleased to show that it was not from want of eloquence he in other instances used a rude and homely style. But whether you read David, Isaiah, and others of the same class, whose discourse flows sweet and pleasant; or Amos the herdsman, Jeremiah, and Zechariah, whose rougher idiom savours of rusticity; that majesty of the Spirit to which I adverted appears conspicuous in all. I am not unaware, that as Satan often apes God, that he may by a fallacious resemblance the better insinuate himself into the minds of the simple, so he craftily disseminated the impious errors with which he deceived miserable men in an uncouth and semi-barbarous style, and frequently employed obsolete forms of expression in order to cloak his impostures. None possessed of any moderate share of sense need be told how vain and vile such affectation is. But in regard to the Holy Scriptures, however petulant men may attempt to carp at them, they are replete with sentiments which it is clear that man never could have conceived. Let each of the prophets be examined, and not one will be found who does not rise far higher than human reach. Those who feel their works insipid must be absolutely devoid of taste.
Institutes of the Christian Religion, Book one, Chapter 9, Sections 1, 2 (first of four parts). John Calvin, 1534