But, if the _flowing_ duration can be easily conceived as the existence of such things as exclude one another, the case is very different with regard to _standing_ duration. For, since we measure all duration by time or by successive intervals, we can scarcely conceive that there may be duration without succession. Even the word “permanence” which we employ in the definition of duration, and which seems to exclude all notion of change, is always associated in our thought with succession and time. The difficulty we experience in forming a concept of standing duration is as great at least as that which we find in conceiving absolute space without formal extension and parts. In fact, formal extension is to absolute space what formal succession is to absolute standing duration. To get over this difficulty we shall have to show that there is a duration altogether independent of contingent changes, as there is a space altogether independent of existing bodies, and that the succession which we observe in the duration of created things is not to be found in the fundamental reason of its existence, as our imagination suggests, but only in the changes themselves which we witness in created things. The following questions are to be answered: Is there any standing duration? and if so, is it an objective reality, or a mere negation of movement? Is standing duration anything created? What sort of reality is it? Is it modified by the existence of creatures? What is a term of duration? What is relative duration? What is an interval of duration, and how is it measured? These questions are all parallel to those which we have answered in our first and second articles on space, and they admit of a similar solution. _First question._--“Is there any duration absolutely standing?” Certainly. For if there is a being whose entity remains always the same without any intrinsic change, its duration will be absolutely standing. But there is such a being. For there is, as we have proved, an infinite reality absolutely immovable and unchangeable--that is, absolute space. Its permanence is therefore altogether exempt from succession; and consequently its duration is absolutely standing.