Institutes of Elenctic Theology by Francis Turretin

The question is not whether the Holy Scriptures are perspicuous in all their parts so as to need no interpreter nor exposition of doubtful passages (which Bellarmine falsely and slanderously charges upon us, stating the question thus: 'Are the Scriptures of themselves as perfectly plain and intelligible as to need no interpretation?''VD 3.1, p. 96. For we unhesitatingly confess that the Scriptures have their heights and depths which we cannot enter or sound and which God so ordered on purpose to excite the study of believers and increase their diligence; to humble the pride of man and to remove from them the contempt which might arise from too great plainness. Rather the question concerns only things necessary for salvation, and indeed as to them, only so far as they are necessary to be known and cannot be unknown without criminality. For instance, the mystery of the Trinity is plainly delivered as to the fact which is necessary, but not as to the how, which we are not permitted to know (nor is that essential to salvation). For as in nature so also in the Scriptures, it pleased God to present everywhere and make easy of comprehension all necessary things; but those less necessary are so closely concealed as to require great exertion to extricate them. Thus besides bread and sustenance, she has her luxuries, gems and gold deep under the surface and obtainable only by indefatigable labor; and as heaven is sprinkled with greater and lesser stars, so the Scriptures are not everywhere equally resplendent, but are distinguished by clearer and obscurer places, as by stars of a greater or lesser magnitude.

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