This chapter contextualizes Vasil'ev's work considering the state of logic in both Russia and Western Europe between the end of the nineteenth and the beginning of the twentieth century, and, above all, the ways in which Vasil'ev absorbed and re-worked input and suggestions flowing from external sources. This survey starts with the individual, Vasil'ev himself, and then moves outwards to isolate and identify the broader contexts within which his ideas developed. Among the main Russian logicians who were important for Vasil'ev there are Matvei Mikhailovich Troitsky, Mikhail I. Vladislavlev, Mikhail Ivanovich Karinsky, as well as the neo-Kantians Aleksandr Ivanovich Vvedensky and Ivan Ivanovich Lapshin. As to the Western scholars, even though Vasil'ev wrote during the years of the foundational crisis of mathematics, he placed great importance on Aristotelian logic and hence on traditional logicians like William Hamilton, John S. Mill, Rudolf Hermann Lotze, Christoph Sigwart, Benno Erdmann, and Wilhelm Wundt. At the same time, attention is focused on the work of some contemporaries like Isaac Husik, Jan Łukasiewicz, Alexius Meinong and Charles S. Peirce, whose work was relevant for the elaboration of non-classical logical ideas around the turn of the century. In particular, the reading of Peirce played an important role in Vasil'ev's elaboration of the idea of a non-Aristotelian logic. Just as important was his acquaintance with Darwin's evolutionary theories through the mediation of Sigwart.