The physical space of the realist period is that of Euclidean geometry and Newtonian physics that affirmed two fundamental ideas – that there is only one space and that it is empty and inert. Euclid defined the properties of the one and only space and of the points, lines, and planes in it. Objects occupy different spaces, but the overarching framework of space itself remains uniform and unchanged by their presence. Newton also held that there is only one space and that it is uniformly extended and unchanging. During the nineteenth century mathematicians suggested non-Euclidean geometries, but the main assaults on the notion of a single and inert space gathered force in the modernist period. In 1901 the French physicist Henri Poincaré defined a multiplicity of visual, tactile, and motor spaces with non-Euclidean and non-Newtonian properties. In 1909 the German biologist Jacob von Uexküll probed the distinctive space-worlds of different animals, further undermining belief in a single space. The social foundation of space was elaborated in 1903 by the French sociologist Émile Durkheim, who explored spaces in different societies that vary according to the social structures established within them and that therefore are not singular or inert. Such plural social spaces subverted the Eurocentrism of the national, imperial, and religious narratives that were based on the presumption that the singular space of Euclid and Newton prevailed during the entire sweep of human history and throughout the universe.