“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…
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.”
–Francis Turretin, Institutes of Elenctic Theology, (2.17.4). Ed. James Dennison (Phillipsburg, NJ: P&R, 1692/1996), 1:143-144.