Nobo, Jorge Luis.  “Whitehead's Principle of Process.”  Process Studies  4 (Winter 1974): 275-284.

Abstract

Whitehead's principle of process has been traditionally taken to mean that the being, or existence, of an actual occasion is its becoming.  In opposition to the received interpretation, I present several arguments showing that this principle, far from identifying the becoming and the being of an actual occasion, assumes that they are two modes of existence exhibited by every actual occasion and establishes that the former mode is creative, or productive, of the latter.  The principle, I conclude, asserts that an occasion qua actual subject (or becoming) creates or produces that same occasion qua actual superject (or being).  [Abstract from The Philosopher’s Index]