 Spatiotemporal separability is a natural restriction to physics of David Lewis’s (1986, p. x) principle of Humean supervenience. It is also closely related to another principle formulated by Einstein (1948, pp. 233–234 of Howard’s (1989) translation) in the following words: “An essential aspect of [the] arrangement of things in physics is that they lay claim, at a certain time, to an existence independent of one another, provided these objects ‘are situated in different parts of space’” (the context of the quote suggests that Einstein intended his principle to apply to objects provided they occupy spacelike separated regions of spacetime).