Lev Mikhailovich Lopatin, the Russian philosopher and psychologist, was one of a number of Russian thinkers—such as A. A. Kozlov—to advance a pluralistic idealism or personalism inspired by the monadology of Gottfried Wilhelm Leibniz. Lopatin was for many years professor of philosophy at Moscow University, president of the Moscow Psychological Society, and editor of the leading Russian journal, Voprosy Filosofii i Psikhologii (Problems of Philosophy and Psychology). He wrote extensively and is famous for the clarity and beauty of his style. His thought owed much not only to Leibniz (and to Rudolf Hermann Lotze) but also to his longtime friend, the Russian philosopher Vladimir Solov'ëv.

Lopatin held that every activity or process presupposes an agent. In his metaphysics there is a plurality of agents, which are spiritual entities (monads), supratemporal, and thus indestructible (since destruction involves cessation of existence...