 However, while there is certainly something in common here, the underlying historical issues are extremely complicated, since they involve subtle questions of scientific and philosophical change. We won’t discuss them in detail in this entry. It is worth emphasis, though, that we should be careful in lumping different people in different epochs together. The precise views they held are often different from one another. As we noted above, and as Lange himself emphasises, Newton did not think that, even in the physical world, all is atoms and the void, since for him there are also forces such as gravity. It follows that any post-Newtonian philosophers who think of themselves as physicalists must have a different thesis in mind from Democritus.