In the chapter "Abstraction," in Science and the Modern World,¹ Whitehead puts forward what he calls "the first chapter in metaphysics." This gives an "account of an actual occasion in terms of its connection with the realm of eternal objects' and harks back to the "train of thought" in a previous chapter "where the nature of mathematics was discussed." More specifically, what Whitehead calls the "analytical character of the realm of eternal objects," which is "the primary mataphysical truth concerning it," is characterized in this chapter in quasi-mathematical terms. We seek in vain in later writings for a more detailed and careful statement as to how eternal objects are interrelated amongst themselves. Therefore this chapter on "Abstraction" seems to contain the key to understanding one very important aspect of the later cosmology. In fact, it has been called "the basic text for the doctrine of eternal objects."² Unfortunately this difficult chapter is usually neglected by commentators, and some of Whitehead's ablest followers say that they have not understood it.