The great moral force of true love lies precisely in this desire for the happiness, for the true good, of another person. This is what makes it possible for a man to be reborn because of love, makes him aware of the riches within him, his spiritual fertility and creativity: I am capable of desiring the good for another person, therefore I am in general capable of desiring the good. (p. 138)
—from Love and Responsibility by Karol Wojtyla (Saint John Paul II)
—The 30 page document John Paul II on Love and Responsibility is a good introduction to the book Love and Responsibility. It is mostly made up of excerpts from the book, but it also includes excerpts from other official and personal writings on love by Saint John Paul II.