John Calvin's Biblical Eyeglasses
The Reformed theologian, John Calvin, said the Bible is like eyeglasses that allow us to see God and without the spectacles of Scripture, we are like an old person with blurry vision and unable to see God or or see God in Creation. In the event of reading the Scriptures in faith, our biblical eyeglasses allow us to see God, and see God in Creation. The Bible does not give us perfect vision, as Biblical Inerrancy wrongly asserts, but we do see God dimly by the power of the Holy Spirit. The Holy Spirit testifies to us, and opens our eyes, and allows us to see as if through a mirror dimly (1 Cor 13:12).
Calvin was practically a pantheist because he believed that we couldn't open our eyes without seeing God, due to the entire world being a "Theatre of God's Glory." However, Calvin also believed that no one is able to see God in Creation because we are all total blinded by our sinful nature (i.e. total depravity). According to John Calvin, in the event of reading the Scriptures through the eyes of faith, the Holy Spirit testifies to us that God is the creator of the heaven and earth as the early creeds say, and eye are opened and we are able to see God clearly through the Scriptures.
Calvin's Biblical Eyeglasses may be found twice in the Institutes of the Christian Religion:
Just as old or bleary-eyed men and those with weak vision, if you thrust before them a most beautiful volume, even if they recognize it to be some sort of writing, yet can scarcely construe two words, but with the aid of spectacles will begin to read distinctly; so Scripture, gathering up the otherwise confused knowledge of God in our minds, having dispersed our dullness, clearly shows us the true God. (John Calvin, Institutes I.vi.1) 
For just as eyes, when dimmed with age or weakness or by some other defect, unless aided by spectacles, discern nothing distinctly; so, such is our feebleness, unless Scripture guides us in seeking God, we are immediately confused. (John Calvin, Institutes, I.xiv.1) 
John Calvin's No to Natural Revelation
Calvin does not believe that everyone who reads the Bible will see that God is the Creator of the world as a matter of fact. I agree with Karl Barth and so I argue that Calvin does not ultimately affirm Natural Revelation. Charles Hodge deeply misunderstood Calvin when he said we should study the Scriptures in the same way as the Sciences study the natural world. We are only able to see through the spectacles of Scripture when we look through them with the eyes of faith. Calvin is not asserting that Natural Revelation is possible through Biblical eyeglasses!
Some argue that Calvin affirms a form of Natural Revelation or Natural Theology based on his famous opening to the Institutes (I.i.1) or other loci, however, the locus of this debate revolves around Calvin's Institutes I.v.12. Even if Calvin's final answer to Natural Revelation is a Yes, that Yes is the smile of a cheshire cat, that has no body to it besides a smile. Calvin is very similar to Karl Barth's position on secular parables at the end of the Church Dogmatics (this paragraph in the Church Dogmatics on secular parables is essentially a commentary on Calvin's Doctrine of Natural Revelation). According to Calvin, the more we search for God through Natural Revelation, the more elusive God becomes, as exemplified by the following quotation from this very section of the Institutes (I.v.12):
Some praise the reply of Simonides, who, asked by the tyrant Hiero what God was, begged to be given a day to ponder. When on the following day the tyrant asked the same question, he asked for two days more, and after having frequently doubled the number of days, finally answered, "The longer I consider this, the more obscure it seems to me." He wisely indeed suspended judgment on a subject so obscure to himself. Yet hence it appears that if men were taught only by nature, they would hold to nothing certain or solid or clear-cut, but would be so tied to confused principles as to worship an unknown god (cf. Acts 17:23) (John Calvin, Institutes I.v.12) 
Reading Genesis with Calvin's Biblical Eyeglasses
Calvin reiterates his Biblical Eyeglasses rubric in the Argument to his Commentary on Genesis, however in this quotation, Calvin demonstrates his opposition to Natural Revelation. Calvin says that Moses' writings on the porto-history (i.g. Gen 1-11) would be superfluous if we were able to discern it through the natural sciences, demonstrating that Natural Revelation does not reveal that God in Creation.
John Calvin's explanation of how Biblical Eyeglasses are used to understand the Creation Narratives (Genesis 1-2):
Now, in describing the world as a mirror in which we ought to behold God, I would not be understood to assert, either that our eyes are sufficiently clear-sighted to discern what the fabric of heaven and earth represents, or that the knowledge to be hence attained is sufficient for salvation. And whereas the Lord invites us to himself by the means of created things, with no other effect than that of thereby rendering us inexcusable, he has added (as was necessary) a new remedy, or at least by a new aid, he has assisted the ignorance of our mind. For by the Scripture as our guide and teacher, he not only makes those things plain which would otherwise escape our notice, but almost compels us to behold them; as if he had assisted our dull sight with spectacles.
On this point, (as we have already observed,) Moses insists. For if the mute instruction of the heaven and the earth were sufficient, the teaching of Moses would have been superfluous. This herald therefore approaches, who excites our attention, in order that we may perceive ourselves to be placed in this scene, for the purpose of beholding the glory of God; not indeed to observe them as mere witnesses but to enjoy all the riches which are here exhibited as the Lord has ordained and subjected them to our use.
And he not only declares generally that God is the architect of the world, but through the whole chain of the history he shows how admirable is His power, His wisdom, His goodness, and especially His tender solicitude for the human race. Besides, since the eternal Word of God is the lively and express image of Himself, he recalls us to this point. And thus, the assertion of the Apostle is verified, that through no other means than faith can it be understood that the worlds were made by the word of God, (Hebrews 11:3.) For faith properly proceeds from this, that we being taught by the ministry of Moses, do not now wander in foolish and trifling speculations, but contemplate the true and only God in his genuine image. (John Calvin, Genesis: Argument) 
Postlude on Inerrancy
This final quotation from the Institutes includes a helpful note from J.T. McNeill (the editor of the Battles translation of Calvin's Institutes). I've included it to show that Calvin did not read scripture as if it were supporting Biblical Inerrancy, Protestant Fundamentalism or any Mechanical Theories of Scripture that purport that the Bible reveals science or propositional logic. It is always possible that we misunderstand the Bible we are reading, or that we do not see perfectly what the Bible allows us to see through it's contents, and even the Bible itself may have defects, errors and contradictions in it, that must be acknowledged as we read the Bible in faith.
"But whether God became known to the patriarchs through oracles and visions or by the work and ministry of men, he put into their minds what they should then hand down to their posterity. At any rate, there is no doubt that firm certainty of doctrine was engraved in their hearts, so that they were convinced and understood that what they had learned proceeded from God.
[J.T. McNeill's note: Calvin does not here offer an explanation of the manner of inspiration in the origin of the Scriptures. However, the suggestion his language conveys is not of a mechanical verbal dictation, but of an impartation of divine truth that enters the hearts of the Scripture writers.]" 
[^Header Image] [By Formerly attributed to Hans Holbein the Younger (1497/1498–1543) - http://library.calvin.edu/hda/node/2384, Public Domain, Link]
[^1] Calvin, John. Institutes of the Christian Religion. Ed. John T. McNeill. Trans. Ford Lewis. Battles. Philadelphia, PA: Westminster, 1960. 70. Print.
[^2] Ibid. 160-1.
[^3] Ibid. 66.
[^4] Calvin, John. "Commentary on Genesis: Argument." Christian Classics Ethereal Library. Ccel, n.d. Web. 05 Jan. 2017. <http://www.ccel.org/ccel/calvin/calcom01.vi.html#vi-p9>.
[^5] Ibid. 70.
Related: bible, Biblical Inerrancy, Eyeglasses, Fundamentalism, Inerrancy, Institutes, institutes of the christian religion, John Calvin, Karl Barth, scriptures, Spectacles