When I use a word, said Humpty-Dumpty in Lewis Carroll’s Through the Looking-Glass, it means just what I choose it to mean - neither more nor less. In the history of Christian theology the tendency to do this has become almost an occupational disease, often making it difficult to understand theologians of the present and almost impossible to understand theologians of the past. Nor does this apply only to thinkers like Berdyaev, who found it necessary to coin his vocabulary as he went along, or to groups like the Gnostics, who sometimes seem deliberately to have chosen nonsense syllables to reveal their theology. It applies as well to those theologians to whom the modern reader feels closest, and to those words and technical terms of which he makes most frequent use