 The fourth challenge is more fundamental. If any of the basic theoretical terms of the many process philosophies, past and present, are to have explanatory value at all, there must be a way to tie the process philosopher’s basic intuition to ordinary experience. After all, the purpose of philosophy is to enhance human understanding, and the core concepts of philosophical explanations must in some fashion be anchored in what we intuitively understand from everyday experience. In fact, some process philosophers (e.g., Whitehead) argue that the traditional notion of substance (a time-invariant, necessarily uniquely located particular) precisely lacks any experiential grounding. On the other hand, substance ontology has been capitalizing on the fact that the canonical illustrations of substances, things or living things, loom large in our practical interactions. The explanatory force of a process ontology thus will depend on whether it is possible to identify a similarly salient canonical illustration for whatever technical notion of process is postulated as basic category. Some process approaches use self-experience as anchoring canonical illustration for postulated technical notions of dynamic sameness and unity, but one might worry that this model is all too complex.