The theme of this volume has been defined as ‘the sources, materials and methods of ecclesiastical history’. After the illuminating, fruitful and often racy subjects which have been discussed in earlier volumes in this series, a theme such as this may at first sight appear to be sober to the point of dullness. I hope to show that it is not, and I make no excuse for presenting it. We are historians, knowing that the study of history is a complex affair, demanding a high degree of imaginative understanding and at the same time a great deal of patient, accurate and often very exacting craftsmanship. Before we can understand what ecclesiastical history is about, either we must go back to its sources, with all the problems of time, language and palaeography which that process entails, or we must at least possess sufficient knowledge to enable us to form some reasonable opinion about the validity of the methods used by those who have cleared the ground for us. Not all historians have the time, or indeed the inclination, to edit texts, but all of us are to an increasing extent dependent upon the work of those who do edit them. A medieval scholar might perhaps have compared the two sides of the historian’s work, the interpretation of ideas and the transcription or calendering of records, to those two great ‘types’ of the contemplative and the practical life, the sisters Mary and Martha. The two were interdependent, and they lived in one house. True, it was the spiritually-minded Mary who chose the good part, while Martha’s obsession with the practical problems of housekeeping earned her a gentle but unmistakable reproof which historians would do well to take to heart.