Peter Fonagy writes that attachment theory holds that there is a universal human need to form close, affectional bonds. Early reciprocal relationships is a precondition for healthy development in all mammals. Proximity-seeking, smiling and clinging are examples of attachment behaviours in the human infant. In optimal conditions these are matched by adult attachment behaviours of touching, holding and soothing which strengthen the attachment bond. The goal of the attachment system is security. Attachment is first and foremost about regulating emotional experiences. It, therefore, lies at the heart of many mental disorders, as well as the practice of psychotherapy.