This book, Hans Kung major work on the nature of the Church, provides a comprehensive picture of its theological image as expressed in the historical forms it had taken through the centuries from the present day back to its origins. As Hans Kung notes in his Preface, there is much talk nowadays about the Church in the secular world but not a corresponding awareness of what the Churches is. To know this we have to know what the Church was originally, and on investigating this we find that the New Testament provides no doctrine of the Church's essence that preceded her initial form. From this it is concluded that essence and form cannot be separated, that the real essence of the real Church is expressed in historical form.