THE old method of philosophizing about theology was the endeavour to prove. This meant, to prove theological conclusions from non-theological premises; otherwise the argument would have seemed circular. Admittedly there were topics of doctrine which did not allow of philosophical proof, but only of historical evidence; divine revelation, for example. To reveal Himself or not was a free choice lying in God's will; that He had revealed Himself was a certainty resting on testimony alone. Yet even in this field there was something for the philosopher to attempt. He could hope to establish a priori and from non-theological premises the possibility, even the naturalness, of revelation; could hope to show that God was such, and man was such, that it was more credible God would reveal Himself to man, than that he would not.