Like “nature,” the term “world” has been reassessed by many but by none so much as Jean-Luc Nancy. He does so in an ongoing and transformative way in many of his writings, often in dialogue not only with philosophers and artists but also with scientists. This article shows that this rethinking of the term is accompanied by a paradigm shift from a foundational architectural metaphor to a contemporary thinking of worlds (in the plural) as ephemeral and contingent constructions with no presuppositions. Nancy’s discussion of the paradigm shift is accompanied by an insistence on bringing about new modes of existence, on transforming habits of thought and action into a habitus that will recompose a world now said to be in perpetual flux.