The book contained dense meditations on the nature of personhood, love, and sexuality, arguing for that order of importance in interpersonal relationships. Wojtyla explains that we have an inherent "sexual urge," which simply means that we are attracted to people of the opposite sex as such. But the way we respond to this urge must recognize other people as persons. He calls this the "personalistic norm." The personalistic norm leads us naturally to love -- a desiring the good for another person. It also keeps us from the sin of utilitarianism, or using other people for our own pleasure, either physical or emotional. Only within the context of love, which keeps us from using the beloved, can we express our sexuality in a full and just way. Wojtyla also explains why the specific context of marriage is the only place where we can act upon the sexual urge without using our partner, and the way birth control stands in the way of the fullness of giving and openness that should exist in the sexual act.
Wojtyla presents a detailed philosophy that rings true with experience, but also describes parts of existence in a new way, which makes for a good read. As I said, however, it is very dense, and the 200-odd pages took me seven-ish weeks to get through, often because I had to force myself to pick up the book, knowing the intellectual task ahead of me... compared to Narnia, which I was reading on the side. However, the ideas should be spread, because our world lacks an understanding of love, and this philosophy helps clear up some confusions that we have.