 Immunology, from its earliest inception, has been concerned with biological identity—its establishment and maintenance. In its original iteration, immunity was conceived as that function that preserved the integrity of the organism in terms of protecting and restoring its individuality. Thus, immune functions testified to the persistence of a stable, core identity defined in terms of its insularity and autonomy. Indeed, individuality undergirded the science from its inception, for the defense against pathogens was framed by an attacked patient (individual) pitted against alien others, the invaders. In this scenario, distinct borders mark individual identity, and immunity is the response to the violation of those boundaries. However, challenges to this conception of immunity have recently appeared. Emphasizing the contextual placement of the organism, notions of demarcated boundaries that have characterized traditional definitions of the organism are being revised.