Pope Paul IV’s Encyclical Humane Vitae (of Human Life) is a short read but what clinched it for me was a talk by Dr. Jeanette Smith called “Contraception Why Not?” You can order it from an organization called One More Soul.
In a nut shell the Church is saying that you can not separate the unitive function of sex from the pro-creative functions of sex. The act of sex was designed by God in a certain way and it is the way that He decided to bring about life including you. If you do not allow for the complete unitive function of sex you inject selfishness into an act which is meant to be an act of total self giving. God gives us life in a total self giving way so His expectation is that we will participate in the act of the gift of life in a giving way.
The way of explaining this next paragraph comes from my opinion as an engineer, but it contains the Church’s concept. The amount of respect you have for a process is related to the respect you will have for the end result. In other words if you have a manufacturing process you will design the process of manufacturing just as much as you will design the end product. The two designs both process design and product design are coupled together. This is also true of the design and creation of people. When we disrespect the design process and turn sex into an act of recreation for the sake of pleasure, we as a society will end up disrespecting the end product which is human life. Pope Paul VI had some incredible prdictions about disrespecting human life in his Encyclical which have come true as a result of wide spread use of contraception.
Another area about the Church’s teaching that has fascinated me are a collection of Pope John Paul II’s Wednesday audiences called “Theology of the Body” Christopher West, has some excellent tapes on this collection of the Pope’s talks. They are not Church authoritative talks, but they are a tremendous gift from Pope John Paul II. The concept that I loved the most from this series of talks is that being created male and female and the sexual union between men and women is a way that we image God as the Trinity. The Trinity is a communion of Persons totally giving of Each Other, One to the Other, Three but One at the same time. A married couple in sexual union are two but one at the same time, becoming three but one at the same time. In this way humanity images God.
A little long and wordy and I hope I didn’t confuse you.
Steve