To return to the Christian Fathers for the origin of many of the beliefs which have sustained our civilisation may seem to be going back a very long way indeed: some people might maintain that we need not pursue the enquiry farther than the Renaissance or even the American Declaration of Independence. But, if we reflect upon the early history of Christendom we shall be surprised not so much that the systematic formulation of Christian dogma took place so early as that it was delayed for so long.