This book explores a hitherto neglected area of theological anthropology: the unity of human emotionality and rationality embodied in the biblical concept of the heart. While the theological contours of human reason have for long been clearly drawn and presented as the exclusive seat of the image of God, affectivity has been relegated to a secondary position. With the reintegration of the body into recent philosophical and theological discourses, a number of questions have arisen: if the image (also) resides in the body, how does this change one's view of the theological significance of human affectivity? In what way is our likeness to God realized in the whole of what we are? Can one overcome the traditional dissociation between intellect and affectivity by a renewed theory of love? In conversation with patristic and medieval authors (e.g., Irenaeus, Tertullian, Gregory of Nyssa, Maximus, Aquinas) and in dialogue with more recent interlocutors (Pascal, Ricoeur, Marion, Milbank, John Paul II), this work pursues a novel theological vision of the essential unity of our humanity.