Throughout his life, Jurij Lotman lived at the crossroad between different worlds, ages, and cultures. The many authors, cultures, and ideas that shaped his thought and influenced his theories are scattered at either side of countless geographical, political, and cultural borders, beginning with the one that separates “Russian culture” from “European culture,” porous and ambiguous as any boundary. The task of reconstructing how Lotman’s ideas came to being, how they shifted their meaning as their context shifted, is more and more a crucial task not only for the historian. Many Lotmanian concepts, first and foremost that of semiosphere, are acquiring major relevance not only for semiotics itself and its branches, such as the rising political semiotics, but also for many neighboring disciplines, such as cultural studies and political sciences. Therefore, gaining a better understanding of the meaning of Lotman’s ideas could be of value also for the applied semiotician or the political analyst. The present paper is the result of research started in the Lotman Archives in Tallin, Estonia. Through an analysis of archival material, it aims at reconstructing the origins and meaning of the most political tropes of Lotman’s theories, especially what I will call his theory of the political subject. In the first part, I will argue that, in order to understand this political aspect of Lotman, it is necessary to take into consideration the intellectual debates inside which the author started his intellectual journey in 1930s–1940s Soviet Russia, and how he sought answers to those debates in the works of G. W. Leibniz. In the final part of the paper, I will try to show how this reconstruction of Lotman’s history could contribute to the contemporary debate in semiotics and other connected disciplines.