What are space and time?

To say that the reality which we all share consists of many kinds of things, and that among those things substances have a certain preeminence, is to leave out important features of that reality if it is not also emphasized that substances change and persist through time and occupy space. I mentioned these considerations in Chapter 4, but it is important that one should try to arrive at some understanding of them. What in particular are space and time? What sort of things are they? One natural answer is that they comprise continua, three-dimensional in the case of space, one-dimensional in the case of time; that is to say that they consist of continuous manifolds, positions in which can be occupied by substances and events respectively, and which have an existence in their own right. It is in virtue of the occupancy of such positions that events and processes are to be seen as taking place after each other and substances are to be seen in certain spatial relations. That cannot be taken as in any sense a definition of ‘time’ and ‘space’, since what I have said about space makes reference to spatial relations, while what I have said about time makes reference to ‘after’, which must be taken in a temporal sense. Nevertheless, what I have said about continua might well be taken as the natural thing to say.