“The Book of the Genesis of the Ukrainian People” is one of the key documents of modern Ukrainian nationalism. It is the most prominent document of the Cyril and Methodius Brotherhood (1846–1847). After N. I. Kostomarov had been arrested at the end of March 1846, he claimed that the seized document was based on “The Books of the Polish People and of the Polish Pilgrimage” by Adam Mickiewicz (1832). This paper compares these two documents and shows the continuity of the Kostomarov work in relation to the writing of Mickiewicz. It also shows the differences which are relevant for the internal logic of the “messianic” philosophy of history and political philosophy. First, in contrast to “The Books of the Polish People and the Polish Pilgrimage,” the main ideas of Pax Christiana are rejected, and the Middle Ages are reconsidered in “The Book of the Genesis” as an age of Christianity’s distortion. Second, in “The Book of the Genesis” there is a purpose to provide a messianic understanding of the Ukraine. Thus, the historical framework is narrowed, and the document provides a universal framework appealing to Slavic nations. It is the Ukraine which can awaken these nations since it latently keeps the principle of the Polish–Lithuanian Commonwealth (“Respublica” or “Rzeczpospolita”), and is able to revive the Commonwealths of Poland and Great Russia. Therefore, “The Book of the Genesis” shows the aspiration for building a national image in terms of Romantic ideas of “historical peculiarity,” and at the same time, clearly indicates the controversies that emerge as a result of following the existing model.