By what right do historians claim that their reconstructions of the past are true, or at least on the road to truth? How much of the past can they hope to recover: are there areas that will remain for ever dark, questions that will never receive an answer? These are problems which should and do engage not only the scholar and student but every serious reader of history. In the debates on the nature of history, however, attention commonly concentrates on philosophic doubts about the nature of historical knowledge and explanation, or on the progress that might be made by adopting supposedly new methods of analysis. The disputants hardly ever turn to consider the materials with which historians work and which must always lie at the foundation of their structures. Yet, whatever theories or methods the scholar may embrace, unless he knows his sources and rests upon them he will not deserve the name of historian. The bulk of historical evidence is much larger and more complex than most laymen and some professionals seem to know, and a proper acquaintance with it tends to prove both exhilarating and sobering – exhilarating because it opens the road to unending enquiry, and sobering because it reduces the inspiring theory and the new method to their proper subordinate place in the scheme of things. It is the purpose of this series to bring this fact to notice by showing what we have and how it may be used.