Not long ago, when I just started to understand historical theory as a philosophy or methodology, I was a little excited. Respectable historians talk about the concepts of history and historiography, the basic methods of studying history and the social manifestations of historical research results, as well as the basic literacy and mission of historians. In such a world, they always seem to try to climb the commanding heights of a certain concept and overlook countless forests in history. However, this is different from Galileo's observation of the still starry sky with the help of astronomical telescope. The work of historical theorists depends on their own eyes, and their research object is the ever-changing history itself, which is not complete and objective. Therefore, their unique work and their more or less philosophical attributes have created an almost outdated academic attitude, and it is also easy for historical theories and researchers themselves to fall into an embarrassing dilemma, that is, excessive abstraction and subjectivity. Obviously, "abstraction" simplifies historical theory into a bunch of empty, boring and puzzling dogmas, and few people in today's society will be interested in such things. Even if there are, few people can really practice these dogmas, even writers themselves; "Subjectivity" makes the historical theory lose its scientific brilliance, that is, its lasting vitality. For example, the decline of Marxist historiography or postmodern historiography in China's academic circles today is because they carry too many subjective presuppositions, so that the process of historical research has almost become a paranoid process of supplementing favorable materials and evidence for these established presuppositions. Of course, this is not worthy of people's full acceptance. Perhaps a scholar has worked hard all his life to reach a conclusion, but this conclusion was suddenly overthrown mercilessly on his deathbed. This is really unbearable, but it is not uncommon in the theoretical circle of history. This makes me believe that many historians who study specific issues are indifferent to historical theory, and it is not completely unreasonable.

However, Karl-I prefer to call him a "historical theorist" rather than a "historian"-is so wise and persistent that he never gives up easily. This amateur history lover has never stopped exploring the theory of history, and has never made his own "What is history?" Fall into the abyss of "excessive abstraction and subjectivity" mentioned above. This classic work in the field of historical theory is systematically divided into six chapters, which respectively expound six different and most striking themes: the subject and object of historical research and their relationship; Historical researchers themselves and their time environment and their relationship; The objectivity and subjectivity of history and their relationship; Causality in historical research; The general path of historical development is progress, decline or cycle; Whether the content of historical research is expanding and enriching. From the content point of view, this thin collection of speeches is full of unpretentious words, profound and unique opinions and a large number of examples closely related to life, which are simple and easy to understand. Therefore, this book is by no means empty talk, nor is it a pedantic article without passion. .