Lovers know that love is both vast and intense. This would seem to make it resistant to philosophical or rational analysis. Yet love's vastness and intensity are what carry it into all spheres of our lives--ethical, political, spiritual, physical. As a result, considerations of what it means to love and to be loved, and what is worth loving and worth being, are inextricable from our most deeply-held commitments in ethics, politics, religion, and metaphysics...