129 short talks (Wednesday addresses at the noon hour, at the time of the daily Angelus prayer) by Blessed John Paul II from 1979-84; these address comprise a biblical reflection of our sexuality as male and female, created in God's image.
"The body, and it alone, is capable of making visible what is invisible: the spiritual and the divine. It was created to transfer into the visible reality of the world the mystery hidden since time immemorial in God, and thus be a sign of it." (John Paul II 2.20.1980)
The idea is that our bodies as men and women don't just have a biological meaning, but an anthropoligical meaning (they speak of who we are as human beings, incomplete by ourselevs and constructed to give ourselves away in love) and a theological meaning (our bodies as men and women are a spousal sign of the image of the triune God who is an eternal communion of persons).
Recall that from the very beginning, God made us in the divine image: male and female. We often miss the key understanding of what it means to be made in God's image. We think of our intellect, or our moral freedom, or our creativity--all facets of the divine image to be sure--but we neglect the reality of our sexuality, and the curious fact that God created two different ways of being human--as man and as woman, each with their own particular genius.
And in creating us male and female, note that he also designed us--he embodied us--so that we would be capable of becoming one flesh, of being united as a true interpersonal communion.
Think about it in these terms, though all human analogies fail. Regarding the Trinity--the Father loves the Son, from all eternity pouring his love upon the Son without reserve. The Son receives that love from the Father and from all eternity pours all his love back upon him. The love between the two of them is so infinite and eternal that it is a third person, the Holy Spirit, who, as the creed declares, "proceeds from the Father and the Son."
Now consider marriage, the bodily image of God's eternal communion of love. The husband loves his wife, pouring all his love upon her without reserve. The wife receives that love and pours all her love back upon him. The love between the two of them is so infinite and eternal that, where God graces, that love becomes a third person, a child, who proceeds from the husband and the wife.
Thus marriage and the family embody the Triune communion of love. Furthermore, married love is a sign that points to the love Christ has for his bride, the Church, for whom he died in that great spousal act of giving his body for her. He continues to express that spousal love at the Eucharistic altar, in which the priest--acting in persona Christi--utters those marital words, "This is my body, given for you."
That's why the sexual union of spouses is the consummating act of marriage--it encompasses all that marriage is, embodying through the one-flesh union the complete self-giving of marriage; the promises made in words at the altar are now made in the body on the marriage bed. The sexual union is a profoundly marital act, in which spouses are saying "I give my whole self to you, all that I am and hope to be, my life and my future."
This helps us understand more profoundly why sex outside of the marriage bed is destructive. Not because the Church has this rule that you'd better follow or you'll make God mad. It's because sex by its very nature is a marital act and thus, outside of the marriage covenant, it is objectively dishonest, a lie of the body.
This also explains the Catholic teaching that contraception objectively distorts the marital meaning of the sexual union of spouses. Fertility is not extrinsic to our identity as men and women; the human person is an integrated whole. Thus to withhold one's fertility in the sexual act, or to ask one's spouse to withhold theirs, effectively compromises the nature of the union--it is no longer about complete self-giving and therefore not a true one-flesh union. Not for nothing do we call them "barrier" methods, whether chemical or physical.
The kind of love we're speaking about--the complete self-donation intrinsic to it--is not something we're capable of apart from Christ's redemption. The fall of humanity effectively disoriented our love, which by nature oriented toward the beloved, marked by profound sacrifice and trust--thus the nakedness without shame in the biblical garden--so that sin has distorted our vision, orienting our desires to selfish grasping and using (i. e. lust). Thus, the shame of nakedness experienced by our first parents when they turned from their Creator, a shame before each other and before God himself.
Christ came to redeem us; to both demonstrate and transform our brokenness. It's no mere coincidence that his first public miracle was at a wedding, or that John the Baptist, when asked if he was the Messiah, commented that he was just the "friend of the bridegroom," or that Jesus, when asked why his disciples didn't fast as John's did, said that no one fasts when the bridegroom is present.
As St. Paul explained, in Ephesians 5, Jesus' own crucifixion--which he freely chose--was/is an act of profound marital love for his bride, the Church. And as St. John experienced in his apocalyptic vision expressed in Revelation, the ultimate end we long for is the wedding supper of the Lamb.
This is why Jesus, when asked about divorce by the Pharisees, referred them not to the Mosaic law (which allowed divorce) but to "the beginning." Moses allowed divorce as a concession to human sin ("hardness of heart"); the Father's true intent was that marriage be a permanent and indissoluble union that reflects the divine image. In saying this, Jesus was indicating a profound truth about his mission--to restore and to redeem that which sin had broken, including (especially?) the sign of God's image within the marital communion of persons.
We were made for love--as John Paul II liked to say, our lives are senseless if we don't experience it and make it our own-- and we are only capable of mature, authentic love through the grace of God in Jesus Christ.