Timothy Snyder presents the often overlooked life and thought of Kazimierz Kelles-Krauz, an important Polish intellectual at the beginning of this century, and thereby opens a new path in the understanding of modern nationalism and twentieth-century socialism. During his brief life in Poland, Paris, and Vienna, Kelles-Krauz influenced or infuriated most of the leaders of the various socialist movements of Central Europe and France. His central ideas ultimately were not accepted by the socialist mainstream at the time of his death. However, ninety years later, we see that his theories anticipated late twentieth-century thought on the importance of nationalism as a social force and the parameters of socialism in political theory and praxis. Kelles-Krauz was one of the only theoreticians of his age to advocate Jewish and Ukrainian national rights as being equivalent to, for example, Polish national rights, and he correctly foresaw the struggle for national sovereignty as being central to future events in Europe.