It is very interesting to investigate Aristotle’s method in defining the notion of space. First he list a series of conditions, which he considers they must hold for place. Then he propose a definition and show that it satisfies the conditions. It is absolutely necessary to avoid philosophical definitions, which attempt to catch the essence of something: part, body, forgiving etc. Indeed we cannot assume that there are “forgiving” and we have to describe it. It is also very difficult to propose a philosophical definition out of the blue, following a method similar to Carnap’s explication. So first of all identifying informally the conditions which we want be satisfied by our definition before giving the latter seems a good idea.