 More also took issue with Descartes’s account of colliding bodies. In Descartes’s system the amount of motion was always maintained at a constant level (guaranteed by God) and this was made manifest in collisions, where motions could be seen to be transferred from one body to another. For More, this seemed too materialistic an explanation, and failed to pay due attention to the role of immateriality. The nub of the matter was that, as More saw it, matter in motion was allowed to explain too much by Descartes. The system could be (as indeed it was) appropriated by atheists, who would simply dismiss God’s role and turn it into an entirely materialist philosophy. Early in his career, More accepted the basic principles of Descartes’s mechanical philosophy, and accepted that “Matter it self, once moved, can move other Matter” (More 1662, in Immortality of the Soul, separately paginated, 21). At this time, More’s immaterial principle of activity, the Spirit of Nature (discussed more fully below), was only introduced to explain phenomena which More believed could not be explained mechanically, such as gravity (More 1662, in Immortality of the Soul, separately paginated, 11). In More’s mature natural philosophy, however, matter was going to be held to be not merely passive but absolutely inert. That is to say, where once More would have accepted that passive matter might be held to carry on moving after being given an initial push (indeed it must do so because it could not stop itself), More later developed the view that matter was completely incapable of moving by itself. Consequently, all activity in any system (even what might otherwise look like merely passive inertial motion) was to be introduced by, or was the result of, the working of immaterial spirit, because immaterial entities were the only entities capable of acting. In the Preface to his Divine Dialogues (1668), for example, More insisted “that there is no purely Mechanicall Phaenomenon in the whole Universe” (More 1668, sig. A6v). By this time, More did not want anything to blur the distinction between non-active matter and active spirit, and so he could not allow that matter might be set in motion and continue to move of its own accord, or by its own nature; this looked too much like matter having activity of its own.