This text offers a critical examination of Leibniz's concept of the monad as a subject, focusing specifically on the problem of its internal unity. The author argues that Leibniz failed to adequately explain what guarantees the "oneness" of the monad, effectively forcing its internal plurality of perceptions into unity by external restriction—namely, the claim that monads have no windows. However, once we admit that a monad may have windows or even doors, allowing for genuine interaction with the outside world, the question of how its internal unity is established and maintained becomes urgent. The text suggests that the term "subject" is particularly fitting due to its etymological roots: a monad must actively constitute its unity by "throwing" this plurality beneath itself (sub-jecting it). Ultimately, the core issue lies in identifying the source of the integrating movement that results in this wholeness. The study thus explores the transition from a static monadology to a dynamic understanding of the subject as an ongoing process of integration.