This text examines the transformation of the concept of "unity" throughout the history of philosophy, comparing ancient perspectives with modern interpretations. The author highlights that for ancient thinkers such as Leucippus and Democritus, the unity of atoms was an inherent and unquestioned property. This ontological stance is rooted in Parmenides’ philosophy, which excluded change and temporality from the concept of the One (HEN). Furthermore, the document analyzes Seneca's view, which links unity exclusively to the process of birth and nature (physis). From this perspective, individual entities are considered secondary in relation to the universe. Individuals are not perceived as integral parts of the cosmic totality but rather as mere quasi-parts. The text thus opens a profound discussion on the ontological status of parts and wholes, exploring how we perceive the cohesion and essence of beings within a broader cosmological framework and historical context.