This book will talk about the mysteries of history. But not about those mysteries that historians themselves talk about: not about the mysterious traces of ancient unknown civilizations, not about mighty cities and kingdoms, from which only names that have been changed over the centuries have come down to us, teasing the imagination, not about great kings and heroes whose names are glorified in legends, but are not found in ancient chronicles. No. There are much more serious mysteries in history, although historians themselves prefer to remain silent about them; these riddles are located not on the outskirts of scientific knowledge, not on the horizon beyond which the unknown begins, but in the very core of that history, which is considered to be well studied, which in school textbooks is calculated in detail by years and events, traced along and across - that is, that the history itself, which we seem to know perfectly well.