 Here we get the impression that Malebranche is thinking that motive force is something additional or added on, as it were, to bodies, and that, in this respect, there is a fundamental difference between the two modes of motion and rest. In other words, whatever causal contribution is needed on the part of God to bring bodies into existence, there needs to be an additional causal contribution on the part of God in the form of a motive force to bring about changes in relations of distance, which occur when bodies are moved. It is as if the default mode of existence for extended substances is to be at rest, and motive force is added on through another divine volition, one that is distinct from the volition that brings the body into existence in the first  place.[18]  If so, this understanding of motion and rest fits well with the PN argument: motive force is not essential to extension because motive force is not only not a relation of distance but rather some additional feature that is added on to bodies, which are by default at rest and passive.