Koestler’s whole purpose in writing this book was to somehow negate antisemitism by proving that Ashkenazic Jews were not Semitic. The fallacy of that purpose, of course, is the idea that antisemitism is at all rational or could be dispelled by any sort of proof. He was neither an historian nor an anthropologist, and most of the experts in those fields who have reviewed the book have point to his highly selective use of sources. moreover, Koestler relies on the use of outdated theories of race as purely biological. The final nail in the coffin, however, of Koestler’s thesis has come in the 21st century, in which genetic testing has shown that, indeed, Ashkenazic Jews are more closely related to Jews of other parts of the world than to other people.