In Calvin's judgment, the biblical story of Noah's ark constitutes "history" in the proper sense of the term (i.e., it happened more or less as described). Calvin is quite concerned, however, to emphasize to his readers that God played an active role -- in the particular form of miraculous intervention -- in every stage of that biblical story. Indeed, he suggests that a failure to recognize miraculous intervention in each chapter of the unfolding drama of Noah's ark-building efforts and subsequent salvation from the flood ultimately serves to cast doubt upon the historicity of the biblical story in question. "If you exclude the extraordinary power of God from this history, you declare that mere fables are related. [...] This entire narration of Moses, unless it were replete with miracles, would be... ridiculous."
Calvin first highlights the element of miracle in this biblical story in connection with Gen. 6.14-15, where the dimensions of the ark are detailed. He notes that "certain profane men [have] ridiculed Moses [for] having imagined that so vast a multitude of animals was shut up in so small a space, a third part of which would scarcely contain four elephants." Calvin seems happy to acknowledge that the ark, at least as described, was too small to contain all the animals, and simply appeals to the "secret and incomprehensible power of God" as sufficient explanation for how they might all have squeezed in regardless of the ark's apparent limitations in space. One gets the impression that Calvin viewed the ark as something akin to one of those magical tents in the world of Harry Potter, which invariably prove much larger inside than they look (or rather, are) from the outside.
Miraculous intervention is again apparent, according to Calvin, in Gen. 7.9, where according to his translation the animals followed Noah into the ark well before the waters were actually unleashed. Interestingly, Calvin believes that Noah and his family were responsible for "collecting from woods, mountains, and caves" the "multitude of wild beasts, many species of which were perhaps altogether unknown," without supernatural help. This, indeed, was part of the extraordinary work which Noah performed in consequence of his remarkable faith. Calvin cannot, however, bring himself to believe that Noah and his family would have been capable of actually getting the animals into the ark when the final boarding call sounded. It took a miracle, then, to get "lions, wolves, and tigers" to willingly board the ark. For that matter, it took a miracle to keep the ark from devolving into a ghastly dinner cruise with "oxen," "lambs," and human beings featured on the menu.
But the clearest instance of divine miracle(s) in the ark narrative occurs in Gen. 7.16-17 in connection with the door of the ark. There is, first of all, the matter of how Noah could, on his own, have closed the door, which "must have been large" enough to "admit an elephant." Scripture makes it clear, however, that Noah accomplished no such thing. Rather: "The Lord shut him in." There is, secondly, the matter of how Noah could have sufficiently sealed the door, once he was in, to prevent water from penetrating and ultimately sinking the ark. In Calvin's judgment, the reality that "the waters... bore up the ark" (Gen. 7.17) is testimony not to Noah's carpentry and/or pitch-spreading skills, but to "the secret power of God," who upheld the ark "by the interposition of his hand." He concludes: "The ark was made secure from the deluge, not by human artifice, but by divine miracle."
Calvin's acknowledgement of miraculous elements in the biblical story of the ark/flood has not been shared by all. In fact, very conservative students of Scripture have been among the most reluctant to acknowledge that the flood narrative smacks of the miraculous. So, for example, the 19th century editor of Calvin's Genesis commentary -- who had a bad habit of interjecting his disagreement with Calvin on trivial matters into the footnotes of the text -- noted in connection with Calvin's judgment of the ark's dimensions: "Calvin takes for granted that there was a miracle, when a close examination" -- i.e., some careful math -- "would have convinced him that there was none." More recent efforts to prove the "feasibility" of the ark/flood narrative without appeal to the miraculous could be observed. John Woodmorappe of the Institute for Creation Research laments the reality that "many sincere believers have felt that the only solution to [a] vast array of 'impossible' difficulties with the Ark [has been] to posit miraculous solutions to them."
Calvin, interestingly, believed it was necessary to acknowledge miraculous elements in the flood narrative long before liberal biblical scholars, with their assumptions of a closed natural universe (not to mention Scripture's fallibility), starting poking holes in the plausibility of the biblical story of Noah. His conviction on this score apparently stemmed from both exegetical observations (for example, the explicit reference to divine agency in the closing of the ark's door) and a bit of common sense (it is surely unlikely that Noah, given the tools available to him, would have succeeded in perfectly waterproofing his floating zoo).
It also, I think, stemmed from sensitivity to the theological significance of Noah's ark. In his concluding comments on Gen. 7, Calvin notes that the Apostle Peter "teaches that Noah's deliverance from the universal deluge was a figure of baptism," and thus of the salvation from sins which the sacrament of baptism signifies and seals (I Pet. 3.20-21). Though Calvin doesn't connect this acknowledgement of the ark as a type (a picture prophecy) of salvation from eternal judgment to the miraculous elements in the narrative, it must have informed his conviction that "the ark was made secure from the deluge... by divine miracle." If in fact Noah had secured temporal salvation from the flood purely by his own efforts (albeit in pursuit of God's rather detailed instructions), what would that say about eternal salvation? Salvation would become a matter of human achievement, a matter of proper compliance to directives given by a God who provides instructions for self-salvation but never intervenes to rescue persons from his own pending wrath, rather than the wholly sufficient work of God for sinners that it properly is. An ark which ultimately proves, no matter Noah's role in constructing it, to be a miraculous (that is, divine) vehicle for salvation points more appropriately to that eternal salvation of sinners which God, not sinners, accomplishes through the work of Jesus Christ and the application of that work through word and sacrament.
In the end, then, the question of whether or not the ark/flood narrative includes miraculous elements proves more significant than it may appear at first glance. But even apart from the typological/theological significance of the ark, it's not entirely clear to me why someone would, unlike Calvin, want to insist that Noah's ark building project and the salvific fruit it bore can be explained without appeal to divine intervention. As Benjamin Warfield famously put it, Christianity is nothing other than "unembarrassed supernaturalism." That being so, it seems appropriate that we not seek to explain away miraculous elements in certain episodes of biblical history, but rather highlight them, defend them, even revel in them. Doing so will, I think, prove more conducive to the sense of awe and wonder that should inform lives lived in conscious relationship to the eternal God who miraculously spoke our world into existence, and by the miraculous incarnation and resurrection of his Son secured our eternal future with him.
Aaron Clay Denlinger is professor of church history and historical theology at Reformation Bible College in Sanford, FL.