From Plato and Aristotle and on to the present, many great philosophers have dealt with the nature of love, which is the most central and profound act of the person. Particularly the philosophy of the twentieth century excelled in this regard, most often inspired by the methods of essential (eidetic) analysis developed and practiced by phenomenology, particularly by realist phenomenology as represented by Max Scheler, by Dietrich von Hildebrand, whose masterwork, The Nature of Love (St. Augustine’s Press, 2009), was recently published in an excellent English translation, and by Karol Wojtyìa in his profound analysis of love in Love and Responsibility and in Man and Woman He Created Them: A Theology of the Body (1987 in Italian, 2006 in a recent translation). One of the key topics of a philosophy of love regards the question whether love is a self-centered act in the service of what Aristotle and Thomas Aquinas regarded as the supreme goal of human life, happiness, to which the beloved person and love would be means, or whether true love is verily an other-centered and other-directed act motivated by the intrinsic value of a person, such that love can truly be called a “value response” – a response to the beloved person for her own sake. According to this last understanding of true love defended in the present work, any hedonistic interpretation of love as springing from a mere desire for pleasure, and also any eudemonistic interpretation of love according to which love would be a mere means to true self-fulfillment and happiness, turn out to be serious misunderstandings of true love. Instead, happiness, however ardently desired by man, is a superabundant fruit of a true love that first turns to the beloved person for her own sake (propter seipsam), and only through a sincere self-donation can reach authentic happiness. The book answers many objections that have been and could be raised against this central thesis about the self-giving and value responding gesture of true love, for example some profound objections raised by Nygren and by Josef Pieper. The book shows the multiple and complex mysterious root of that value and intrinsic goodness of the person that motivates love. He shows that the genuinely self-transcending and self-sacrificing gesture of love is fully compatible with a motivating role, but only with a subordinated and co-motivating role, of happiness in love, while happiness always remains principally and primarily a fruit of true love and self-donation, rather than its motive.