The interpretation of the historical process is now a major academic industry. Just as we have bibliographies of bibliographies, we have histories of historical writing. Indeed, the day is not far distant when, in history as in metaphysics, the third degree of abstraction will triumphantly be reached: a history of histories of history. The historians, those who of all men should be urging most strongly a return to the sources, are also those who lead us to the most rarefied heights of speculation about our nature and destiny. The field of history should be for ever unenclosed, and be a free breathing-space for a pallid population well nigh stifled with the fumes of philosophy.’ In the forty years since Augustine Birrell wrote The Muse of History, the Green Belt has become a built-up area; the pallid population now suffocates in libraries beneath the weight of reviews and journals whose learned footnotes tantalize with hints and glimpses of pastures long submerged.

When the theologian ventures on to this scene, the historian may well despair. Understandably, he hesitates before subscribing to Professor Toynbee's declaration that history passes over into theology. ‘It is a bad habit in historians to take at their face value the hysterical exaggerations of the pulpit'; it is also a bad habit to turn to first causes when secondary ones will do. That may be why ecclesiastical history is reckoned a soft option by those academics who rate hard-headedness as highly as any man of business.