At the start of the "Preface" to Man's Vision of God Hartshorne points to the "mountainous — I had almost said, monstrous — mass of writings devoted to "philosophical theology' " and asks what there is left for him to add. His reply is "exactitude, logical rigor."¹ What he claims here "simply, if without apparent modesty," has been one of the major characteristics of his publications in the succeeding half-century. Whereas, for instance, it may not be possible to arrive at "a trouble-free interpretation" of Whitehead's theological views (and, according to Hartshorne, Whitehead himself "said once that he felt that his thought about God was "very vague,' but that others would be able to clarify the matter" ²), Hartshorne has made important contributions to theistic thought by discriminating analyses of the contents of such notions as those of the divine necessity, perfection, relations, power and awareness. In this respect he has considerably clarified the concept of God not only for process theology but also for theological understanding generally.