The problem of how physical systems, such as brains, come to representthemselves as subjects in an objective world is addressed. I developan account of the requirements for this ability that draws on and refines work in a philosophical tradition that runs from Kant throughPeter Strawson to Gareth Evans. The basic idea is that the ability torepresent oneself as a subject in a world whose existence isindependent of oneself involves the ability to represent space, andin particular, to represent oneself as one object among others in anobjective spatial realm. In parallel, I provide an account of howthis ability, and the mechanisms that support it, are realizedneurobiologically. This aspect of the article draws on, and refines,work done in the neurobiology and psychology of egocentric andallocentric spatial representation.