Many columns have been written about the "secrets" of a happy marriage, as if the difference between a happy marriage and an unhappy one is that in the former the spouses know some truths which are unknown to everyone else. The presumption is that, if these truths can get conveyed to you, then your marriage will be happy too.

But practical truths and rules, which is what these "secrets" are, do not work that way. They are never really hidden, because people who earnestly wish to know them can usually discover them for themselves. And we get no benefit merely from knowing them, but only from following them. It does no good for a woman simply to know that she shouldn't nag, or for a man simply to know that he shouldn't dominate. It's the not nagging and not dominating that counts. So discussions of the "secrets" of a happy marriage are basically worthless.

But "mysteries" are a different thing entirely. Mysteries do benefit us simply by our knowing them. And mysteries can only be learned from someone who reveals them, as they cannot be discovered simply through an earnest search.

Let us define terms. A mystery is a truth which pertains to God, and which is so profound that it cannot be completely fathomed. We can make progress in understanding it, but the deeper we get in grasping it, the deeper and more unfathomable the truth seems to us.

Mysteries are marvelous and evoke wonder, because they seem to involve something which cannot be, and which may even seem contradictory -- like God become man, or three persons in one God. Yet mysteries are not really contradictions, and, as they are powerful and true, they "break" those merely human views which allege that they are impossible. Mysteries are signs of contradiction which cause the rise and downfall of human apprehensions.

Happy marriages must be grounded in mysteries. A husband and wife who want to have a happy marriage must accept these mysteries. Similarly, anything which denies the mysteries pertaining to marriage is inimical to marriage. For example, a prenuptial agreement, in reducing marriage to a cunning contract, destroys the mystery of marriage.

There are four mysteries of marriage. The first is that husband and wife become one flesh. Therefore, it is not that divorce is not permitted, but rather that divorce is a metaphysical impossibility. What is called "divorce" is mere human convention, and, to the extent that it is successful, it is as if a man had cut off part of himself, and he does not survive the procedure whole. Husband and wife's being one flesh is deeper than conversation, sex, dates, or shared responsibilities. It is intuitive and prior to language. It is a way of being. This is a mystery because it looks impossible that two should become one --and yet they do.

The second mystery is that a married person will be judged by God chiefly on how he lives his marriage. The way the Church explains this, is to say that a Christian's baptismal vocation is taken up and given a specific shape when he becomes married, so that, for him, being a Christian and being married to this particular person are indistinguishable. Alternatively, we can say that marriage is not a mere contract but a sacrament. As it is holy, it needs to be entered into with the fear and reverence which suits something holy, and all human ambitions should be subordinated to it. This is a mystery because it looks impossible that our eternal welfare could hinge on how we deal with a particular person in perfectly ordinary things -- and yet it does.

The third mystery is that marriage, when properly lived, is inherently fertile, even if the couple is sterile. Marriage mirrors the incarnation, and yet the Word of God does not come down from heaven to earth, and the seed of the Gospel does not fall to the ground, in vain. Marriage as the basic cell of society radiates out its love to the broader society beyond, just as the transforming energy of the Eucharist radiates its grace from the person who receives it in Communion.

Man and woman falling in love look like they could wrap up themselves in each other's embrace and remain there forever, and it seems impossible that such a love could serve to renew the whole world -- but in marriage it does.

The last mystery of marriage is about the happiness of marriage which these other mysteries insure, not a happiness of contentment and receiving, but rather the happiness of pouring oneself out in a gift, in forgiveness, service, and death. To be happy in marriage is to make a sacrificial gift of self to the other. It seems impossible that happiness may be found only in sacrifice -- and yet it is.

One may perhaps see that the mischief of artificial contraception lies in its attacking the mysteries of marriage. A contracepting couple exchange the metaphysical unity of marriage for a mere coincidence of pleasure. They exchange its holiness for something profane. Instead of the inherent fertility and energy of marriage, they choose sterility and boredom. And they would even eliminate the cross by eliminating sacrifice and risk.

All of the mysteries of marriage are illuminated by the life of Christ, as indeed "the mystery of man is made manifest by the mystery of Christ."

Michael Pakaluk is Chairman and Professor of Philosophy at Ave Maria University.