The starting point of this work is the realization that, under the name of love, very diverse things are hidden. Pieper takes his inspiration from (and constantly cites) one of the key works for understanding this issue, The Four Loves by C. S. Lewis, whom he justly calls “the great lay theologian of our time,” and whose title is, in itself, meaningful.
But Pieper’s novelty lies in his vindication of Eros, in contrast to Protestant theology, which had condemned it as being opposed to pure love, to Agape. Eros, says Pieper, is necessary in order not to lose oneself in a love so supernatural that it becomes disembodied, and also not to succumb (perhaps by reaction) to what is purely carnal, which is not love. Benedict XVI would later take up these concepts in his encyclical Deus Caritas Est.
With this approach, it becomes clear that the book is essential for overcoming the confusions surrounding this issue that our civilization has suffered from for many centuries — and not only within the Protestant sphere.