In this chapter, I define the structure of time and space. I begin by constituting time as an objective feature of nature, by showing how, based on the laws of nature, the relations of simultaneity and precedence can be given objective meaning, and how distances in time can be measured. Next, I introduce and develop the notion of space by giving meaning to the idea of locality and defining spatial relations in terms of the temporal order of reciprocal determinations. Finally, I show that there is a fundamental constant speed of determination between occurrences in space, and further explain how this can be used for measuring space. The entities in space and time are shown to be reciprocally determining elements, which are themselves constituted by temporo-spatial relations.