Something is destroyed by the council’s teaching, but not philosophy. What is actually abolished is a too-simple idea of how revelation and so-called unaided reason are related. In fact, revelation and reason are in intimate converse, each one entangled with the other. In the first place, revealed truth about man’s nature presupposes the natural law. In the second place, it underwrites reflection upon it. More to the present point, supernature illuminates the natural realities with which human reason is concerned. This is true in an immediate and direct way for those who acknowledge that this revelation is true. What I hope to show is that in an indirect way it is even true for those “men of goodwill” who do not.
Now there are two ways in which one might inquire about these matters, two ways to investigate how the mystery of man is illuminated by the mystery of the Word. One way is to focus solely on the Word Incarnate, Jesus Christ. Now this Man was God. Because we are not God, it might seem that this fact tells us nothing about ourselves, but the sheer fact that the human and divine could commune in a single person brings out with shocking clarity the depth of the older teaching that the one is the image of the other. The sharpest, clearest definition of human nature is simply imago Dei. In surrender to God, then, we lose nothing; only in Him can we discover ourselves.
Or consider the hope of redemption, grounded in Christ’s death and resurrection. The fact that this directly concerns our destiny rather than our nature does not make it irrelevant to our nature. What it tells us is that it was no mockery for the Creator to set eternity in the hearts of men, that the thirst for Himself with which He endowed us can be satisfied after all, that we can drink from Him forever. Perhaps there is no logical contradiction in the idea of an image of God who is destined to futility, but there is certainly a performative incoherency in it. As Benedict XVI points out, hope that life will not end in emptiness is a requirement of our nature: “Only when the future is certain as a positive reality does it become possible to live the present as well.”
The approach that I have just described -- considering only what Christ shows us about ourselves -- may seem to be the high road. But although the mystery of the Word made flesh is the highest arch of the structure of revelation, the Word was not imparted to us only in the flesh. All expressions of the Word are connected; we do not throw away scripture, sacrament, and apostolic teaching because we have Christ. In reality, everything in revelation illuminates the mystery of man. This more general matter is what I wish to explore.
I mentioned three ways in which revelation is related to natural law. It presupposes natural law in that it makes no sense without it. Time after time God commends His commandments to our admiration. “What great nation is there,” He asks the children of Israel, “that has statutes and ordinances so righteous as all this law which I set before you this day?” Plainly the question expects the Israelites to compare the relative righteousness of the verbally revealed ordinances of God and the humanly enacted ordinances of other nations. But how can they compare, unless they have the power of comparison? How can they have such a power, unless they already know something about righteousness? And how can they already know something about it, unless God has already revealed that something by other means? We find the same pattern throughout the word of God: Even when His disclosures exceed what natural reason could have figured out for itself, we can distinguish them from nonsense. They depend on natural reason for their intelligibility.
Revelation underwrites rational reflection on the natural law by acknowledging the ways in which created reality itself is a kind of revelation; nature itself bears a kind of testimony to the truths of its Creator. A law is written on the heart, even in the person who “has not the Law.” We bear a certain order and design, which gives the way we are put together a significance it could not have if it were merely the unintended result of an accidental sequence of events. The principles of this design can be recognized -- for example, the complementarity of the sexes. Finally, our actions have natural consequences; the law of the harvest, that we reap as we sow, is not a mere product of the myth-maddened mind. This fourfold testimony teaches us, in a manner not unlike the way in which the properties of soil and seeds instruct the farmer. Experience assists human wisdom because Eternal Wisdom has seen to it that it shall; the universe has been designed to make this possible.
More to the point of this series, supernature illuminates the natural realities that are the business of natural law philosophy by inviting the intellect to reason more fully and adequately about matters that it may in principle be capable of finding out on its own, but rarely does. Philosophy has rightly been called a preamble to theology; but theology is also a preamble to better philosophy. An everyday parallel may make this clear. Persons of my own sex often fail to notice things that ought to be perfectly obvious, and are in fact obvious to most women. “Have you seen my glasses?” “Yes, you’re holding them.” “Are we out of milk?” “Turn around; it’s on the table.” “Why did Sheila speak so unkindly to that young man?” “Because she likes him.” Philosophy is like that too. The facts of created reality may be right under our noses without our noticing. We may be nearly blind to them until their Creator says, “Look here,” as the pagan thinkers were nearly blind to the sacrificial quality of love. Does this “look here” allow natural law thinkers to dispense with arguments accessible to nonbelievers? Obviously not, but it allows them to peer into the phenomena of our common life with greater confidence and penetration than they otherwise could. It provides hints and insights about all sorts of matters which natural reason can later confirm by its own proper methods. So reason grasps the things within its ken more quickly, deeply, and surely when revelation calls attention to them.
Astonishingly, it also grasps these natural realities more readily when supernatural realities not within its ken are revealed to it -- as we will see. But to see this we need more equipment -- say, a prism.
Through the prism of revelation, at least five different colors of light shine on the natural realities. We may call these preceptive, affirmative, narrative, promissory, and sacramental. Although these lights clarify every facet of our nature, for simplicity I deal mostly with the facet of conjugal sexuality. One cannot talk about everything, and the Word made flesh did after all perform His first supernatural miracle at a wedding. I make no claim to break new ground concerning sexuality per se. The purpose is merely to show how the natural and supernatural realities are related.