The depth of love
In this book, Lewis argues that the depths of love are withheld from from human perception by the limits of various kinds of desire. For instance, the depth of each kind of love can be limited in one's perception by dramatic irony if they believe other people exist for their own wish fulfillment. In family love, this means obligating one's family to do what you wish they would do. In romance, eros becomes sadomasochism, and agape is completely obscured by personal desire.
The religious aspect of love
According to Lewis, love is an inextricable part of religion, and vice versa. He says that a person is born with an innate desire to be loved, but the quality of love that defies human fathoming is the most essential, needed part, he argues. Ironically, one cannot attain happiness unless one understands love, but how do we understand love? He explains that love is demonstrated in its purest form in the Christian mythology of the New Testament, because in that story, God has nothing to gain by loving us, but he does love us, when we deserved it least (this is a classic C.S. Lewis argument).
Pleasure and irony
Lewis writes that ironically, pain and pleasure are often ways to misunderstand love. For instance, one wants love to feel like pleasure, but true love often feels like torture. We are lured into eros, for instance, by the lure of physical sexual pleasure, but the lust of human sexuality is inherently ironic, says C.S. Lewis, because the best case for eros is that it leads to marriage and trust, which are inherently sacrificial, painful experiences. Eros is a tricky love, as are they all, he shows.
The need for love
What if one says, "I don't need love anymore." Is it possible? Lewis explains how humans are enslaved to their need for love. He explains through metaphysical religious argument that various aspects of divine love are necessary for life to exist, and he explains that in the daily comings and goings of daily human life, love is a need just like food or water. This is ironic, because love often falls under the lens of desire; we want love. But Lewis bumps up the intensity, saying we actually need it in a primal way.
The essential complication
There is an ironic tension therefore, between the way humans need reality to be and the way it is. This tension is ironic, because it is the theodicy; if God is love, and if love is necessary for life, and if God loves us, then why does God allow so many people to exist so apart from love? What then, is the nature of hatred? Of loneliness? Of suffering? Lewis shows in his arguments about agape that perhaps reality itself is being complicated by a tension whose resolution comes in an eternal love awaiting us after we die. He appeals again to the Christian myth.
