This text examines the philosophical relationship between identity and alterity, arguing that these two concepts are inextricably linked. The author posits that identity is not a static state but rather an event-like process and a relation to oneself, which necessitates a continuous return to the self. This dynamic is inherently tied to the concept of the subject, as only a subject possesses the capacity for self-reflexive return and internal unity. It is specifically within the subject that we find uniqueness, which serves as an essential foundation for understanding multiplicity. Multiplicity is not merely a plurality or a summation of items; it encompasses alterity—the mutual difference and separation of distinct entities. Even in instances of external similarity, an ontological otherness remains, defining the boundaries of subjectivity. The work thus emphasizes that without acknowledging the unique subject and its relationship to otherness, it is impossible to adequately grasp the nature of human existence or the structure of the world as a whole.