ABSTRACT. This paper concerns Part IV of Whitehead’s treatise Process and Reality, in particular the chapters IV.II and IV.III. Most considerations in Part IV have to be seen as fundamental and profound, and not at all incomprehensible. We have to admit that some of the considerations have implications which on a first reading may look quite paradoxical (for example the idea that Democrit’s atomism lies at the foundation of a Heraclitean dynamic), but this may be regarded as a special appeal. Part IV has to be considered as an independent text which has been inserted without proper adaptation.