 At least among those theologians who posited both atoms and accidents in their ontology, most changes were explained in terms of one accident’s being replaced by its contrary or at least by something acting like a contrary. In this case the atom changes, not the accident, which in fact is annihilated by its contrary. Although accident-replacement was the most general account of change, changes that involve one type of body coming from another type of body (as for example when fire is produced from burning wood or a spark is produced from striking stones together) presented a special case that needed a different analysis of change. Many theologians explained this sort of change in terms of a theory of latency (kumūn), which maintained that the fire atoms were already present in the wood or stone, albeit latent in them, and then were made manifest through the action of burning or striking.